The Geomorphic Role of Riverine Processes in Carmel Lagoon Water
The Geomorphic Role of Riverine Processes in Carmel Lagoon Water Surface Eleva on and Sand Bar Breaching Dynamics for the Carmel River‐Lagoon Biological Assessment Report Prepared for: Monterey County Resource Management Agency
Prepared by: Edward D. Ballman, P.E. and Anne E. Senter
January 2014 Riverine Processes, Carmel Lagoon EPB, SRPS, and ISMP Project
TABLE OF CONTENTS
1 INTRODUCTION 1 1.1 Project Description 1 1.2 Purpose and Objectives of this Report 2 1.3 Literature Review 2
2 NATURALLY FUNCTIONING LAGOONS ALONG THE CALIFORNIA COAST 3 2.1 Natural Sand Barrier Breaching Behavior 3 2.2 Natural Perched Lagoon Morphology 4 2.3 Natural Closed Lagoon Conditions 4 2.4 Natural Surface Water-GW Interactions 5 2.5 Ecosystem Benefits of a Naturally Functional Lagoon 6
3 IMPLICATIONS OF IMPAIRED LAGOON BEHAVIOR 8 3.1 Impaired Sand Bar Breaching Behavior 8 3.2 Impaired Lagoon Morphology during Open Conditions 9 3.3 Impaired Conditions during Lagoon Closure 9 3.4 Impaired GW-Surface Water Interactions 10 3.5 Ecosystem Effects of an Impaired Lagoon 10
4 IMPAIRED PROCESSES IN CARMEL LAGOON 12 4.1 Deleterious Impacts Related to Artificial Sand Bar Breaching Behavior 16 4.2 Impaired Conditions Related to Artificial Sand Bar Breaching Behavior 16 4.3 Impaired Lagoon Morphology during Open Conditions 21 4.4 Impaired Conditions at Lagoon Closure 25 4.5 Impaired GW-Surface Water Interactions 28 4.6 Impaired Conditions Related to Carmel Lagoon Ecosystem Health 30
5 ANTICIPATED RESPONSE OF CARMEL LAGOON TO PROJECT IMPLEMENTATION 32 5.1 Anticipated Sand Bar Dynamics without Artificial Breaching 33 5.2 Anticipated Lagoon Morphology 34 5.3 Anticipated Conditions at Lagoon Closure 34 5.4 Anticipated GW-Surface Water Interactions 35 5.5 Anticipated Ecosystem Effects 35
6 REFERENCES 36
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TABLE OF TABLES
Table 1. Carmel Lagoon first seasonal breach of each year 18 Table 2. Carmel Lagoon breaching events and days open to ocean 22 Table 3. Carmel Lagoon water surface elevations and estuary surface areas pre- and post-breaching 25 Table 4. Carmel Lagoon final season closure dynamics 26 Table 5. Carmel Lagoon perched morphology dynamics 27
LIST OF FIGURES
Figure 1. Carmel Lagoon WSE and streamflow, WY2012 15
APPENDICES
Appendix A. Water surface elevations in Carmel Lagoon and streamflow in Carmel River at Highway 1 gage, WYs 1993-2012.
Appendix B. Compilation tables of riverine dynamics of breaches and closures, WYs 1993-2012.
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1 INTRODUCTION
1.1 Project Description
Carmel Lagoon Ecosystem Protective Barrier (EPB), Scenic Road Protection Structure (SRPS), and Interim Sand bar Management Plan (ISMP) Project
The Carmel River Lagoon, located at the mouth of the Carmel River, is a very productive estuary which serves as rearing habitat for juvenile, federally listed South- Central California Coast steelhead. The Carmel River was designated as critical habitat for South-Central California Coast steelhead in September 2005. The ecosystem in and around the Carmel River Lagoon also supports other federally listed species such as the California red-legged frog, western snowy plover, and Smith’s blue butterfly, and numerous other special-status species.
The Carmel River drains approximately 255 square miles of the Santa Lucia and Sierra de Salinas Mountains into the Carmel Bay. About 270 acres of the Carmel River Beach and Lagoon are owned by the State of California/California Department of Parks and Recreation (State Parks). Other property owners within the Lagoon include Carmel Area Wastewater District (16 acres), Carmel Unified School District (9 acres), City of Carmel- by-the-Sea (6 acres), and Homestead Inn/Mission Ranch (16 acres). Public and private stakeholders have worked together over the past decade to identify best management practices that would maintain the Carmel Lagoon in a more natural state (MPWMD, 2007).
The Carmel Lagoon Ecosystem Protective Barrier (EPB), Scenic Road Protection Structure (SRPS), and Interim Sand bar Management Plan (ISMP) Project (hereafter referred to as Project) is a comprehensive plan meant to promote improvement in ecological function of the Carmel Lagoon, including natural floodplain function and improvement of habitat for threatened and endangered species within the existing lagoon. The goal is to allow the lagoon to breach naturally, without increasing flood risk to private structures and public facilities. The EPB would provide protection from flooding to low-lying homes and other local Carmel-by-the-Sea infrastructure along the north edge of the Lagoon. The SRPS would provide protection along the northern sand cliffs from erosion associated with lagoon-ocean processes that might occur if sand bar management were to cease. The ISMP is an interim sand bar management plan meant to provide a short-term solution to potential flooding issues with select sand bar breaching actions that allow additional natural function in the lagoon while still protecting properties and infrastructure, with the understanding that the development
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of the EPB and SRPS lead to potential long-term solutions that return the Lagoon, its sand bar, and associated riverine and ocean dynamics to more natural cycles.
1.2 Purpose and Objectives of this Report
The main objective of this report is to summarize both natural and impaired processes associated with the Carmel River Lagoon ecosystem from a riverine perspective. To do so, we present a descriptive hydrologic characterization of (1) how lagoon systems function naturally in Coastal California, (2) how current and past management practices impair Coastal California lagoon systems, (3) a quantitative and qualitative assessment of recent Carmel Lagoon function, and (4) an assessment of how implementation of the Project will work to restore more-natural functions in Carmel Lagoon. The term lagoon will be used in this report to represent both lagoonal and estuarine functions (i.e., systems closed and open to the ocean, respectively). Quantitative measures will be identified where possible to supplement qualitative findings from this and other lagoon systems.
1.3 Literature Review
Existing literature was reviewed to understand how naturally functioning lagoon systems along Coastal California promote healthy ecosystems for aquatic species, including steelhead. Further literature review revealed information on how management practices can negatively affected lagoon habitat.
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2 NATURALLY FUNCTIONING LAGOONS ALONG THE CALIFORNIA COAST
Lagoons found along Coastal California have unique qualities with respect to semi-arid Mediterranean climate conditions, geologically active tectonics, relatively small watershed areas, and riverine processes associated with frequency and duration of lagoon openings and closures (Jacobs, et al., 2011). Streamflow plays a critical role via seasonal and episodic variability in the temporal pattern of lagoon openings and closures, and thus has a large effect on specific geomorphic and environmental conditions such as sand bar breaching behavior, lagoon morphology during open and closed conditions, groundwater-surface water interactions, and habitat quality. Such conditions are key drivers in the ability of aquatic and terrestrial species to successfully survive and thrive within this environment.
2.1 Natural Sand Barrier Breaching Behavior
The dynamics associated with a natural sand bar breach depend on the morphology of the sand bar itself, river discharge, and wave dynamics (Smith, 1990). In a naturally functioning lagoon ecosystem on the California coast, sand bar breaching occurs during the winter rainy season. Streamflows increase as rains begin. Depending on the watershed and precipitation patterns, flows may fill the lagoon to the point where riverine forces overcome sand bar stability and an outflow channel breach is created that releases impounded waters into the ocean.
Sand bar breaching can occur via an accumulation of low flows or from an abruptly larger flood flow. The outflow channel, once open, additionally provides a route for tidal flows to enter the lagoon. The morphology and elevation of the outflow channel to the ocean are important factors in the availability of lagoon habitat (NMFS, 2008; Alley, 2013), while water surface elevation (WSE), volume and depth of the lagoon are functions of streamflow as well as tidal fluctuations and ocean swells.
When low flows fill a lagoon to its full volume and then breach the sand bar, a sinuous outflow channel can develop, creating a pathway based on beach slope, sediment size, and longshore wave patterns (Smith, 1990; Thornton, 2005). Large flow events on the other hand, may create a breach at a point perpendicular to the bar resulting in a shorter and more direct outlet to the sea. But once a flood flow diminishes, it is likely that the outlet will migrate toward a pathway based on beach slope, sediment size, and longshore wave patterns.
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2.2 Natural Perched Lagoon Morphology
Perched lagoon morphology is defined by NMFS (2008) as a lagoon with a WSE above mean high tide, and can refer to fresh water lagoons with closed sand bars as well as to lagoons where fresh water flows out to the ocean over the sand bar at the lagoon’s mouth. Summer wave action that tends to deposit sand onto beaches helps build up beach berms (Jacobs et al., 2011). This elevational increase can create perched lagoon morphology by formation of a high berm combined with an outflow channel that provides the greatest ratio of fresh water to saline water during open-bar dynamics, as well as providing the highest lagoon WSE upon closure.
2.3 Natural Closed Lagoon Conditions
In Coastal California environments, with their associated dry-Mediterranean summers, streamflow generally decreases through the spring and into the summer months. As flow recedes, riverine processes are progressively less able to overcome the opposing ocean forces driving sand up and onto the bar. Eventually, this leads to the seasonal closure of the barrier bar at a point when river and any (generally small) groundwater (GW) inflows to the lagoon system are not sufficient enough to maintain an open outflow channel. The WSE associated with the final lagoon closure of the year is related to the morphology of the lagoon and whether the outlet channel is in a perched or non-perched state. When the outflow channel is perched (i.e. at a higher elevation and in an advantageous position that maximizes fresh water lagoon habitat), the initial WSE will be higher, thus accumulating an increasingly higher ratio of fresh water to brackish water while river discharge continues.
Because tidal exchange occurs until a sand bar closes, saline waters are generally present within the lagoon at closing. Salt water is denser than fresh water and thus tends to stratify into the lower layers of a lagoon. Conversion from highly saline conditions to more fresh water conditions occurs when fresh water river discharge forces salt waters against the inland side of the closed sand bar (Coates and Guo, 2003; NMFS, 2008). Because of stratification, a forcing mechanism exists at the boundary between the two layers. The upper wedge of fresh water pushes the salt water wedge against the porous sand bar. If there are enough fresh water flows, three processes can occur: entrainment, which carries a mixture of fresh water and salt water into the ocean if a shallow or intermittent channel remains open to the ocean; mixing, which de-stratifies the lagoon and blends the stratified layers together, moderating salinity values; and seepage of salt water through the permeable sand bar and out of the lagoon (Smith, 1990; Debler and Imberger, 1996; NMFS, 2008; Zhang et al, 2008). All of these processes can play a role in the conversion of a lagoon to fresh water. The
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conversion can take more than a month after sand bar closure (Smith, 1990), and generally depends on continuation of fresh water flows into the lagoon.
An additional element in these complex systems is that of ocean waters entering the lagoon while the sand bar is closed. This occurs primarily through wave overtopping, but also through seepage into the lagoon through the sand bar—seepage can occur in either direction and is mainly a function of tides (Watson and Casagrande, 2004). Seepage out of the lagoon may happen when tides are out, while seepage into the lagoon may happen when tides bring waves onto the beach and against the sand bar.
Overtopping is a function of wave energy. Higher energy waves crash onto a sand bar and overtop it, adding small to large volumetric quantities of salt water to the lagoon (Thornton, 2005; Moffatt and Nichols, 2013). Along the California coast, wave energy decreases in the late spring and summer and increases in the fall and winter. The addition of salt water into the lagoon in late summer/early fall while the lagoon remains closed increases WSEs and salinity values in the lagoon, generally lowering water quality shortly before rains begin to contribute streamflows, which then provide relief with better water quality (Hayes et al., 2011).
2.4 Natural Surface Water-GW Interactions
Once a coastal lagoon is in a closed configuration, WSEs and water quality are governed by a balance of outflows (seepage through the bar and evaporation), the aforementioned salt water inflows, and fresh water inflows (stream baseflow and GW inflows).
With the degree of variability in Mediterranean climate conditions in California, most lagoon systems experience some degree of closure under natural conditions (Jacobs et al., 2011). From a fresh water fisheries perspective, ideal summer conditions would occur when waters of a closed lagoon system convert to fresh water before streamflows stop, be it in late spring or over the summer, depending on flow persistence. When streamflows cease, GW inflows from the local aquifer become the single source of additional fresh water influxes into the lagoon system, and must partially counteract evaporation rates and barrier bar seepage rates, at least to some degree, if fresh water conditions are to be maintained over the course of lagoon closure.
GW aquifer storage levels are predicated on antecedent hydrologic conditions of the previous and current year, and potentially over a longer time frame following drought conditions or excessive GW pumping. In a best-case scenario, there would be no GW
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pumping or instream diversions, and aquifer storage capacities would be at potential maximums depending on precipitation and runoff. In many Coastal California settings, GW storage has been greatly reduced by mechanical pumping of water for agriculture and municipal uses. At the bottom of a coastal watershed, salt water and fresh water ‘compete’, such that salt water can encroach landward into fresh water aquifers. When fresh water aquifers are full enough, gradients that push seaward generally keep salt water intrusions from encroaching into fresh GW supplies (Jacobs et al., 2011). When excessive GW pumping creates over-drafting of the aquifer, a fresh water gradient reversal can occur, and seawater intrusions can infiltrate into local coastal water supplies. Such dynamics are of great concern to coastal communities (e.g. Johnson, 2007). GW inflows into lagoons become important particularly once surface flows cease for the summer, and are the only counteractive to evapotranspiration in terms of fresh water inflows.
Persistent GW seepage likely occurred in lagoons along the coast prior to GW extractions and continues today in some systems, potentially providing fresh water supplies for good quality habitat during yearly lagoon closures. Pumping likely has reduced GW contributions to lagoon ecosystems, depending on local conditions (PWA, 2007). A comparison of two instances showed that a GW gradient indicating a small but valuable GW input rate relative to the potentially progressive decline in water quality through the dry summer months has been found in Carmel Lagoon (Larson et al., 2006), while numerous springs and seeps in the vicinity of Elkhorn Slough have disappeared since the 1940’s, likely due to GW pumping (Van Dyke and Wasson, 2005).
2.5 Ecosystem Benefits of a Naturally Functional Lagoon
Naturally functioning lagoon ecosystems provide myriad, year-round benefits to aquatic and terrestrial species, including high habitat diversity, abundant invertebrate food sources, and refugia from predators and other environmental stressors (Cannatta, 1998). Steelhead thrive in conditions where abundant invertebrates are found (Larson et al., 2005). Tolerance capability of invertebrates to salinity provides a good indicator of the ability of the system to support good rearing habitat for steelhead (NMFS, 2008; pers. comm. J. Pearson-Meyer, 2013).
In California when lagoons are opened in the winter season by river discharge, full mixing of fresh water and salt water can provide opportunities for fish to thrive (Smith, 1990). When lagoons close at the beginning of the dry season, river discharge generally is still flowing at low rates, in which case with enough end-of-season inflow the lagoon can naturally convert from stratified saline conditions to fresh water conditions. In fresh water conditions, studies have shown that steelhead smolts have a higher survival rate
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and greater growth rates (Smith, 1990) as well as greater densities in lagoon systems (NMFS, 2008, Table 12). Steelhead smolt growth rates in Scott Creek Lagoon, California were higher than those rearing in the upper watershed, leading to conclusions that lagoon habitat conditions that promoted steelhead growth and survival were strong predictors of ocean survival (Hayes et al., 2008; Bond et al., 2008).
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3 IMPLICATIONS OF IMPAIRED LAGOON BEHAVIOR
Lagoon ecosystems found along Coastal California have experienced high degrees of modification due to human interactions. Development of towns and cities and associated infrastructure has had multiple negative effects on these ecosystems (Van Dyke and Wasson, 2005). Impaired lagoon/estuarine ecosystems are not able to provide the full range of benefits to aquatic and terrestrial species that are required for healthy ecosystem function. Modifications leading to impaired lagoon ecosystem function include: alteration of the natural cyclical opening and closure of the lagoon by breaching and closing the sand bar artificially; encroachment onto the lagoon floodplain via infill, built structures, and agricultural uses; channelization of the river; diversions of streamflow; GW pumping; and loss of sediment supply via hardening of channel banks and damming.
Although each modification could be discussed in depth, this chapter will focus on alteration of the natural cyclical opening and closure of the lagoon by breaching and closing the sand bar artificially. The negative impacts associated with manipulation of natural barrier bar processes can propagate through each water year and potentially beyond, producing negative effects to bar morphology, sediment transport, water quality, and water volume in the coastal lagoons.
3.1 Impaired Sand Bar Breaching Behavior
Artificial barrier bar breaching can negatively affect lagoon health by promoting formation of a wide and deep outflow channel that removes large quantities of sand from the beach. This can cause fresh water to flush from a lagoon into the ocean prematurely and at a rapid rate, likely opening the lagoon earlier than if a natural breaching regime were in place. Once fresh water has been flushed, the often deep and direct outlet channel allows large quantities of seawater into the lagoon, which results in an abrupt increase in salinity levels that may not be tolerated by aquatic organisms, particularly juvenile fish.
Salinity gradients drive other water quality parameters such as temperature and dissolved oxygen. When salinity concentrations are high, lagoons stratify and the saline layer sinks to the bottom. Dissolved oxygen concentrations decrease, and high salinity promotes heat absorption, raising temperatures (NMFS, 2008). In Pescadero Creek, artificial sand bar breaching has led to steelhead die-offs, likely caused by very low dissolved oxygen concentrations (Smith, 1990; Sloan, 2006). Increased salinity can drive fish into shallower waters, exposing them to increased predation and potential
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stranding, forcing out-migration of fish before they are ready for the ocean environment, and decreasing productive lagoon habitat (Smith, 1990; NMFS, 2008).
3.2 Impaired Lagoon Morphology during Open Conditions
Since wave action continually moves sand onto and off of beaches, and streamflows may not be large enough to keep a breach open, there are instances where artificial breaching is performed multiple times a year in order to promote an open lagoon condition (Smith, 1990; e.g. MPWMD, 2013). This intermittent disruption of lagoon waters suggests that what should be equilibrium conditions within the lagoon prior to natural opening are instead punctuated with large spikes of abruptly changing water quality. Eventually, streamflows may be large enough to keep an outlet channel open, yet if the channel has been artificially placed, it is unknown where a natural channel would have formed, where it potentially would have moved to, or what geometry such channels would have had in the case where natural breaching occurred.
When artificial breaches are cut across a beach directly perpendicular to the river mouth, this practice could affect any further evolving morphology of the outflow channel and the remaining beach berm. This action could propagate through the year, leading to a situation where the outflow channel is at a low elevation and ocean water tidal flows are able to move freely into and out of the lagoon. Fresh waters that form a lens on top of saline waters could then be carried out to sea when tides recede. This process could continue throughout the yearly open cycle until the sand bar closes for the summer (J. Pearson-Meyers, pers. comm., 2013).
3.3 Impaired Conditions during Lagoon Closure
Salinity measures provide strong evidence of whether a lagoon has converted to fresh water after bar closure. If the outflow channel geometry brought about by artificial sand bar breaching is wide and deep, fresh water accumulating in the lagoon is largely flushed with each tidal cycle, precluding the ability of the lagoon to retain high quality aquatic habitat. This flushing occurs because fresh water is less dense than salt water, so if the outlet elevation is low, more of the stratified fresh water lens is preferentially removed. Atkinson (2010) found that artificial breaching in the San Gregorio Lagoon consistently raised salinity values at sampling stations.
If streamflows are low at lagoon closure, high salinity concentrations can create very poor quality habitat conditions very quickly, which can lead to fish die-offs (Sloan, 2006). Persistent flows are needed over a long enough period of time to convert the lagoon to relatively fresh water after seasonal closure. However, when beginning at a deficit compared to what natural conditions might provide conversion of the lagoon to
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a relatively fresh water condition may not be possible depending on a particular water year’s streamflow condition and how long low flows persist upon closure.
Additional salinity impacts can emerge due to preferential evaporation of the fresh water lens and wave overtopping events, which occur regularly in fall and winter months along the California coast. GW becomes the only potential fresh water source once streamflows cease, a source that may be muted depending on local consumptive use and GW extraction practices. If so, an impaired GW condition can potentially magnify water quality impacts associated with outflow channel geometry brought about by artificial sand bar breaching.
3.4 Impaired GW-Surface Water Interactions
Lagoon WSEs are controlled by a number of factors when the barrier bar is closed including timing of riverine flow cessation, initial WSE at closure, GW supply in aquifer storage at the beginning of each dry-summer season, anticipated regional GW pumping, the hydraulic gradient of the GW aquifer and its relationship to sea level, through-bar seepage rates, and evaporation.
Lagoon WSE at the time of seasonal closure can have a direct effect on potential GW inflows, due to hydraulic gradient conditions at the coast between infiltrating seawater and fresh water aquifer storage (Johnson, 2007). If seawater intrusions are occurring, there is little chance that fresh water GW will be able to percolate out of the substrate. Lagoon stage and GW levels have been shown to have a strong correlation, as reported via Feeney (2002) in Watson and Casagrande (2004).
GW pumping can have negative effects on the overall watershed flow regime. These effects may manifest as early cessation of streamflows in early summer. A consequence may be diminished GW gradients, resulting in a reduction in GW flow into coastal lagoons if GW elevations were impaired by pumping. These considerations show that high WSE at lagoon closure is important because GW flows may not be consistent enough or of sufficient volume to help maintain lagoon water quality through a dry season.
3.5 Ecosystem Effects of an Impaired Lagoon
Artificial breaching at the beginning of the rainy season results in significant habitat losses that can reduce lagoon volume and area by as much as 80 percent of pre- breach values (Whitson, 2013). Depending on streamflow volume and breach timing, artificial breaching can occur hours to weeks prior to natural breaching. In all cases where artificial breaching occurs, aquatic habitat conditions are negatively affected. If
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an artificial breach creates high rates of lagoon emptying, juvenile steelhead can be pushed into the ocean prematurely (Allen, 2013). Smith (1990) found that after artificial breaching, some steelhead were flushed from lagoons but some also remained; differences in lagoon morphology and topography may play a role in the ability of fish to find refugia under these circumstances.
In San Gregorio Lagoon, California, a sampling program showed that water quality declined when the barrier bar was breached repeatedly in the summer, preventing maintenance of the lagoon as a body of relatively fresh water. Survival rates declined; seining found reduced numbers of steelhead from early summer to late fall, and dead threespine stickleback fishes were found stranded in dewatered sections of the lagoon (Atkinson, 2010).
In a study covering water quality and habitat conditions in lagoon ecosystems along California’s Central Coast, Smith (1990) concluded that the two most important management recommendations to promote high degrees of water and habitat quality were: (1) to pay close attention to the amount of streamflow diverted from the system, as a decrease in flows impacts the ability of lagoons to convert to fresh water conditions during the summer dry months, and (2) noted that in the case of the lagoon systems under study, Pescadero Creek, San Gregorio Creek, and Waddell Creek, artificial opening of the lagoons severely altered habitat conditions, adversely affecting steelhead abundance and growth rates.
This brief review of a small number of concepts and case studies is but an indication of the damage that has occurred in lagoon ecosystems due to modification and alteration of dynamic natural ecosystem regimes.
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4 IMPAIRED PROCESSES IN CARMEL LAGOON
Having gained an appreciation of natural and impaired processes associated with Coastal California lagoons, a focused examination is now needed to understand how the Carmel River Lagoon ecosystem has been impacted by various management actions. Many studies have been conducted over the past 10 to 20 years to better grasp ecological conditions in the Carmel River watershed and the Carmel Lagoon (e.g. Watson et al., 2001; Watson and Casagrande, 2004; James, 2005; Thornton, 2005; Urquhart, 2013). Studies have been initiated in part by the Water Allocation Program Final Environmental Impact Report, prepared in 1990 for the Monterey Peninsula Water Management District (MPWMD), by subsequent California Environmental Quality Act monitoring requirements, which sought to insure compliance with mitigation measures (MPWMD, 2013), by the Caltrans mitigation bank project in 1997 that excavated the South Arm of the lagoon, and in order to document the Carmel River Lagoon Enhancement Project that excavate the South Arm an additional 3,000 feet toward Highway 1 in what is called the Odello West area (James, 2005).
The Carmel River Watershed has large variations in seasonal and yearly discharge rates, brought about in large part by the unique nature of the coastal California geographic location within a Mediterranean climate zone, as well as by the size, vertical extent, geology, and geomorphic structure of the watershed. Carmel Lagoon, located at the bottom of the watershed, serves as an ecological interface zone between the watershed and the ocean. The Lagoon is generally not connected to the ocean during times of very low or zero streamflow, when ocean waves build a barrier beach (sand bar) across the mouth of the lagoon and close the outflow channel. When river inflow is relatively low and the Lagoon is not open to the ocean, a dynamic equilibrium is reached between streamflow and groundwater inflows, outflow through the barrier beach, evapotranspiration, and ocean wave overtopping. In summer this leads to lower WSEs and in the fall prior to opening, abrupt increases in WSE can occur due to overtopping. As streamflows increase in the fall and early winter, Lagoon WSEs can rise to flood stage depending on precipitation patterns. When flooding does occur, infrastructure along the northern edge of the lagoon and within the Lagoon floodplain, are threatened before the sand bar would typically open naturally.
In response to the flooding scenario, since at least the early 20th century the sand bar has been mechanically managed (breached) in order to lower WSEs to below flood stage. Since 1973, emergency sand bar management has been carried out by the County of Monterey (County), Monterey County Water Resources Agency (MCWRA), and State Parks. On average in recent years, at least one artificial breach has occurred yearly, with as many as three or four management breaching actions occurring in some
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years. When the annual rainy season ends and the sand bar may have not yet closed off naturally, the decision may be made to mechanically close the sand bar before streamflows subside entirely, in order to maximize the volume of water in the lagoon for the dry season. This practice seeks to mitigate early-season artificial breaches that opened the Lagoon and promoted deeper, wider outflow channels than might otherwise have formed.
Following the designation of the Carmel Lagoon as critical habitat for South-Central California Coast steelhead in 2005, concern has grown about adverse impacts in Carmel Lagoon associated with artificial breaching activities that, while serving to protect local infrastructure, also dramatically alter natural ecosystem functions in the lagoon. The National Marine Fisheries Service (NMFS) suggested a northerly sand barrier breach in winter 2005, as this pathway is known to maintain a higher WSE in the lagoon, thus providing better habitat (MPWMD, 2007). The northerly outflow channel was considered a success in that WSEs in the Lagoon were maintained at a higher elevation at high river flows that reached upwards of 5,000 cfs. An unintended consequence of the northerly outlet path was that erosion occurred along the toe of the local bluff, potentially threatening homes and the Scenic Road in Carmel-by-the-Sea. The erosion of the bluff likely occurred because of the confluence of high flood flows and ocean wave activity creating waves 22 to 26 feet in elevation. The bluffs experienced sloughing once the waves receded. A similar event occurred in 2008 when the outlet channel was directed to the south. In that case, the northern bluffs were eroded in a similar fashion independent of flood flows and outlet channel position.
A technical advisory committee was formed to address maintaining the current level of protection for built infrastructure within the context of complying with the Endangered Species Act’s requirements of reducing impacts to endangered species and returning the lagoon to a natural function state. The committee subsequently produced a long- term adaptive management plan for Carmel River State Beach and Lagoon (MPWMD, 2007). This document set in motion the development of potential solutions that would return the Lagoon to a more natural state that provides necessary ecological functionality for steelhead and other species that inhabit and depend on the system, while also ameliorating the potential increase in flood risk to surrounding infrastructure that could result from compliance with federal law. The current set of potential solutions is termed the Project in this document, as explained in the introduction. Technical studies including this one are addressing the complex natural, physical processes and interactions of the lagoon, beach, and ocean in order to provide the necessary studies needed for stakeholder to make informed decisions (e.g. Alley, 2013; Moffatt and Nichols, 2013; Whitson Engineers, 2013a,b).
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From a riverine perspective, data associated with a 20-year record of Carmel River streamflows and Carmel Lagoon WSEs encompassing water years1 (WY) 1993-2012, are presented in Appendices A and B. Appendix A contains WSE and streamflow data in graphical form. These figures and associated data in Appendix B can be used to compare general WY conditions, but should not be considered as an unimpaired dataset, as the Carmel River-Lagoon watershed has been heavily managed for decades, including within the timeframe of these data.
Summary statistics were collected into a series of tables and are reported herein as Tables 1-4. The tables consist of (1) flow and WSE values and relationships with lagoon breaching behavior, (2) WSE and lagoon surface area relationships pre- and post- breaching, (3) breaching events and days open to the ocean, (4) and lagoon closure dynamics.
Figure 1 of Appendix A, the WY2012 WSE and flow graphic, was annotated to help orient the reader with the information available in the 20 years of data found in Appendix A2.
1 Water years (WYs) are defined as October 1 of the preceding calendar year through September 30 of the named year. For example, WY 2012 encompassed October 1, 2011 through September 30, 2012. 2 Figure 1 annotation data on artificial breaching dates and closure dates were taken from the 2011-2012 Annual Report for the MPWMD Mitigation Program (MPWMD, 2013).
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Figure 1. Carmel Lagoon WSE and streamflow, WY2012 Appendix B contains specific date, time, and WSEs related to all breaches and closures as defined below. When compiling Appendix B, thresholds were defined in order to produce a consistent dataset. All referenced WSEs are reported in the NAVD88 datum3. Definitions are provided in the notes section of each WY summary table in Appendix B, and are explained here as follows:
. “Sustained closure” is from October 1st of each WY until the first breach. . In a “temporary breach”, the lagoon remains open to tidal influences for < 7 consecutive days.
3 Water surface elevations (WSEs) in this study are based on the North American Vertical Datum of 1988 (NAVD88). Lagoon WSE is recorded in NGVD29, so all WSE records were adjusted upward by +2.74 feet based on information from the National Geodetic Survey. For instance, an NGVD29 elevation of 10.00 feet was adjusted to an NAVD88 elevation of 12.74 feet. Mean tide level in nearby Monterey Bay is 3.01 feet NAVD88.
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. In a “sustained breach”, the lagoon remains open to tidal influences for > 7 consecutive days. . “In-season closures” occur when lagoon WSE > 11 feet persists for > 24 consecutive hours during the winter-spring time period in each WY when the lagoon is generally persistently open to the ocean rather than in a dry-summer closed state. . “Early closures” occur when the lagoon is mostly closed and WSEs increase to a point that would be considered a final closure, but then the lagoon opens up again briefly for about a week to a month prior to final closure. . “Final seasonal closure” (FSC) is when the lagoon closes for the last time with receding river flow and does not open again until the following WY. The date chosen is when obvious tidal influences cease. . A “significant increase” in WSE occurs only in the dry season, and is almost always associated with a wave-overtopping event, but can also occur due to river flow. In either case, a rapid increase in lagoon WSE of 1-foot was selected as ‘significant’. . “Total days of closure” was calculated as the sum of the number of days between the start of a WY on October 1st and the initial breach, plus the number of days between final season closure and the end of the WY on September 30th, plus the number of days of temporary closures.
4.1 Deleterious Impacts Related to Artificial Sand Bar Breaching Behavior
The primary impacts related to the lagoon environment due to sand bar management and the artificial timing of lagoon breaching, are as follows: Impacted lagoon WSEs throughout the year during both open and closed conditions; rapidity and magnitude of lagoon drainage; extent of salt water intrusion; stratification dynamics in the lagoon; water quality in the lagoon; and habitat loss and deterioration for steelhead and California red-legged frogs, as well as other aquatic and terrestrial species. Further, physical impacts to the sand bar have a profound effect on: where the outlet channel forms and subsequently moves over the course of the open-lagoon condition; where river sediments transport offshore and deposit; where beach sands transport offshore and deposit. This leads to loss of sand necessary for the formation of the beach, bluffs and sand bars, and causes the breakdown or non-formation of natural protective barriers at the beach, bluffs and along the shoreline. All of these impacts will be discussed in greater detail in the following sections.
4.2 Impaired Conditions Related to Artificial Sand Bar Breaching Behavior
In the Carmel River-Lagoon ecosystem, among other similar Coastal California systems, riverine dynamics play an important role in lagoon dynamics and, at least to some
Balance Hydrologics, Inc. - 16 - Riverine Processes, Carmel Lagoon EPB, SRPS, and ISMP Project degree, drive “whether, when, and for how long” the lagoon is open, while the formation of the sand bar beach and configuration of the outlet channel are somewhat more wave-dominated processes (Jacobs et al., 2011). The dual role of river processes and ocean dynamics can be seen in the Carmel Lagoon during California’s summer dry season, as streamflows dry up (in part due to GW extractions and streamflow diversions), and ocean forces deposit sands onto the beach that are structurally capable of keeping the lagoon closed. Likewise in the winter season, streamflows can gradually fill the lagoon and breach the sand barrier, or suddenly generate fresh water forces strong enough to overcome ocean forces for extended periods, depending on the timing, duration, and quantity of rainfall and runoff.
In the Carmel River Lagoon, artificial breaching has disrupted seasonal flow and sediment dynamics for decades, directly impacting aquatic and terrestrial habitat (PWA, 2007). Historical, artificial breaching actions have had consistently deleterious effects on Carmel Lagoon habitat conditions, which differ significantly from what would have occurred with a natural opening and closing regime (e.g., MPWMD, 2011).
Table 1 shows that in WYs 1993-2012, the first breach of each WY was mechanically assisted with the exception of WY2008. In WY2008the combination of flow conditions and wave action compromised safety. In WYs 1993-2000, management action generally occurred when WSE exceeded 11.5 feet (L. Hampson, pers. comm.), which assured that adjacent properties would not flood. From 2000-2010, management activities were not generally undertaken until lagoon WSE and streamflow forecasts showed that WSEs were likely to exceed 12.8 feet, the elevation at which houses would begin to flood. This threshold has gone up in recent years due to the adoption of adaptive management techniques including sandbag placement. Currently (WYs 2011 and 2012), a WSE of about 13.2 feet triggers breaching, with some room for maneuvering based on anticipated flow and/or wave action (CL-MOU-2012).
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Table 1. Carmel Lagoon first seasonal breach of each year Days between Number of Table 1. Carmel Lagoon first seasonal breach of each year Daily mechancial breach days from first Mean Date of and assumed breach until Flow on assumed natural opening of lagoon Water Date of first Days into Mechanical day of natural Days into the lagoon outlet summer Year1 Wate Year Type2 breach3 WY or Natural4 breach breach5 WY channel6 closure7 (date) (days) (cfs) (date) (cfs) 2012 Dry 11/25/2011 56 Mechanical 18 12/16/2011 77 21 174 2011 Above Normal 11/24/2010 55 Mechanical 19 12/19/2010 80 25 238 2010 Above Normal 10/14/2009 14 Mechanical 759 10/14/2009 14 0 271 2009 Normal 2/16/2009 139 Mechanical 749 2/16/2009 139 0 91 2008 Normal 1/5/2008 97 Natural 509 1/5/2008 97 0 114 2007 Critically Dry 2/11/2007 134 Mechanical 29 2/16/2007 139 5 37 2006 Wet 12/28/2005 89 Mechanical 81 12/31/2006 92 3 170 2005 Wet 12/30/2004 91 Mechanical 532 12/30/2004 91 0 194 2004 Below Normal 12/30/2003 91 Mechanical 416 12/30/2003 91 0 120 2003 Normal 12/16/2002 77 Mechanical 1250 12/16/2002 77 0 197 2002 Below Normal 12/3/2001 64 Mechanical 402 12/3/2001 64 0 178 2001 Normal 1/11/2001 103 Mechanical 148 1/11/2001 103 0 141 2000 Above Normal 1/24/2000 116 Mechanical 1000 1/24/2000 116 0 100 1999 Normal 11/3/1998 34 Mechanical 21 11/23/1998 54 20 233 1998 Extremely Wet 12/6/1997 67 Mechanical 112 12/6/1997 67 0 270 1997 Above Normal 12/9/1996 70 Mechanical 27 12/10/1996 71 1 154 1996 Above Normal 12/13/1995 74 Mechanical 36 12/21/1995 82 8 184 1995 Extremely Wet 1/9/1995 101 Mechanical 445 1/9/1995 101 0 201 1994 Critically Dry 2/17/1994 140 Mechanical 106 2/18/1994 141 1 404 1993 Wet 1/3/1993 95 Mechanical 85 1/7/1993 99 4 173 Summary Statistics Average 85 337 90 4 182 Median 90 130 91 0 176 Maximum 140 1250 141 25 404 Minimum 14 18 14 0 37 Standard Deviation 33 367 30 8 79 Notes 1. Water Year (WY) is defined as October 1 of one year to September 30 of each subsequent year, for instance WY 2012 encompassed Oct 1, 2011 through September 30, 2012. 2. WY type as designated by MPWMD. 3. Date of first breach is defined as that in which the lagoon area > 2 feet in depth declines by > 20%. 4. The lagoon has been breached since the 1930's (CCoWS, Fall 2007), and in recent decades to prevent infrastructure flooding. 5. Date of assumed natural breach used an assumed seepage rate and known inflows that traced predicted changes in lagoon WSE and volume (Whitson Engineers, 2013b), and then calculating date of assumed breach, using a WSE of 15 feet as the arbitrary elevation at which breaching would occur. 6. Number of days where artificial breaching opened lagoon earlier than natural processes. Calculations were not performed in increments of less than a day. 7. First breach was mechanically initiated in each year of this analysis (with one exception in 2008 due to safety issues), even when days between mechanical and assumed natural opening of the outlet channel were zero.
An analysis of the day of mechanical breaching versus calculations estimating the day of natural breaching over WYs 1993-2012 showed that in nine of the 20 years analyzed (45% of the time), the lagoon was artificially breached at least one day earlier than the predictions calculated for the day of natural breaching. In three of those years artificial breaching occurred earlier than predicted by 20 days or more (Table 1). WYs 2011 and 2012 may have been anomalous, as alternative breaching techniques were being used
Balance Hydrologics, Inc. - 18 - Riverine Processes, Carmel Lagoon EPB, SRPS, and ISMP Project to create shallow, pre-graded outlet channels rather than a wide and deep outlet channel, resulting in lagoon WSEs staying above 9 feet upon the initial breach, as shown in Figure 1 (MPWMD, 2013). Alternatively, in WY1993, 1994, 1996, and 1999 WSEs initially fell to about 5 feet, resulting in essentially full evacuation of the lagoon. Artificial breaching significantly reduces lagoon volume, which has a negative effect on volumetric and surface area habitat that remains following emptying (Casagrande et al., 2002). Whitson Engineers (2013b) calculated a volume of 13.7 acre-feet at 4.74 feet of WSE versus a 382 acre-foot estimate for total volume when WSEs are at 12.74 feet (i.e. near the current artificial breaching threshold; CL-MOU-2012). At elevations of 15.74 feet, which would allow higher WSEs than typical breaching patterns now but well below a 17.5-foot Project EPB top of wall, lagoon volume is estimated as 804 acre-feet. This suggests that the implementation of the project could more than double the volume of the lagoon at a maximum WSE of 15.74 feet, providing an example of the significant increase in WSE during closed conditions, and likely additional days of closed lagoon habitat.
Review of mean daily flow on the day of breaching (Table 1) shows that in the nine years in which artificial breaches were performed at least one day prior to calculated predictions of natural breaches, flows were less than 110 cfs in each case. For the Carmel River-Lagoon system, a conservative estimate was calculated by James (2005) suggesting that natural breach events would occur when flows were 200 cfs or greater. According to NMFS, analyses showed that in the years 1989-2010, approximately 80% of the time artificial breaching occurred at flows lower than 200 cfs, providing an indication that the lagoon has been prevented from functioning naturally during those times.
One might conclude from reviewing Table 1 that as long as flows are above approximately 200 cfs, there are no negative impacts associated with artificial breaching. This conclusion would be incorrect. Artificial breaching creates effects to the beach that may last for months to years, and which affect natural processes year- round. When the barrier bar is artificially breached in high-flow years, the breach is often made at the shortest distance between the lagoon and the ocean, generally due west (James, 2005). This initial opening may ‘set’ the beach with a structurally altered bar morphology, causing evacuation of sand via sediment transport mechanisms that may have otherwise remained on the beach. These altered physical processes and the associated inherent instability likely cannot be reinstated quickly by new sand filling in the breach. Consequently, this may alter the beach for the entire year, and potentially beyond.
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As specified in Section 4.1, there are numerous deleterious effects from artificial sand bar breaching that extend far beyond the simple act of mechanically opening the sand bar. For instance, once the sand bar is mechanically breached, all subsequent lagoon WSE fluctuations and sand bar opening-closure scenarios could be considered impaired. In most years, this impairment causes the lagoon to empty rapidly due to the initial position of the mechanically created outlet channel. For example, when the outlet channel position and orientation is mid-bar and straight out to the ocean (a condition that would not have occurred naturally), salt water intrusion into the lagoon is extensive during the upper spikes in tidal fluctuations. This behavior is easily seen in the magnitude in WSE differences on a daily basis in the figures in Appendix A. Lowest recorded WSEs have shifted slightly over the years, likely due to new equipment placement. In recent years, the water surface drops below the pressure transducer at the gage station in the southern arm of the lagoon at about 4 feet NAVD (James, 2013, pers. comm.). Water volume evacuation from the lagoon is very extensive at these levels (Whitson Engineers, 2013b). These intense cycles create significant disturbances to stratification dynamics as the lagoon begins to close, with higher ratios of salt water intrusion preventing important oligohaline conditions (where a gradient of fresh water to saline conditions establishes appropriate salinity and habitat conditions for aquatic species at more than one shallow depth) to form at the appropriate time, as should happen when perched-lagoon conditions prevail and tidal influences are muted. Stratification rather than oligohaline conditions leads to poor water quality for steelhead, California red-legged frogs, and other aquatic and terrestrial species that depend upon fresh water conditions within the lagoon over the summer months.
Impairment caused by a reduction in the fresh water lens can eliminate the fresh water habitat provided by the lagoon and can create an inhospitable environment because of low water levels, high salinities and low dissolved oxygen concentrations. The influx of seawater creates a salinity-stratified lagoon and alters potential lagoon productivity as well as water quality because the availability of fresh water may become compromised. When the denser seawater that has breached into the lagoon naturally sinks within the water column, it pushes fresh water to the surface, creating a narrow, shallow fresh water lens. Then, during subsequent breaches or tidal fluctuations of inflow and outflow in those times when the lagoon is not in a perched configuration, there is a greater likelihood that the heavier salt water will remain in place while the upper fresh water lens gets mixed or drains away. This type of situation leads to poor habitat and water quality conditions, and the only area in the lagoon that remains viable steelhead habitat is the small, shallow fresh water lens at the lagoon surface coupled with what amount may be replenished via fresh water groundwater influx (Casagrande and others, 2002; Watson and Casagrande, 2004). These conditions do not lead to the
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oligohaline lagoon environment necessary to provide suitable habitat for steelhead and other aquatic species that over-summer in Carmel Lagoon.
From a physical perspective, mechanical breaching impacts the development and direction of an outlet channel that responds to ocean wave, longshore transport and riverine dynamics in its formation. Mechanical breaching does not allow natural development of the outlet channel in a physically-driven direction. With respect to a northerly position of the outlet channel, westerly mechanical breaching prevents delivery of riverine sediments just off-shore where such sediments might build up to attenuate wave dynamics against the northern bluffs. In addition, sand bar ‘blow-out’ results in loss of sand and gravels into the offshore canyon, rather than shoaling just off shore in the northerly direction. Removing or preventing offshore natural barriers to form increases the risk of ocean swells to the bluff and surrounding infrastructure. Lagoon seepage rates to the ocean may also be affected during the dry season due to removal of hardened sands on the lagoon side of the barrier bar that could potentially form. Mechanical breaching likely eliminates some of the potential for hardening of barrier beach sand on the lagoon side of the beach. Considering decades of artificial breaching—as illustrated very clearly over the last 20 years (Table 1)—it may take a number of years after artificial breaching ceases before the sand bar begins to behave naturally.
4.3 Impaired Lagoon Morphology during Open Conditions
Carmel Lagoon is primarily open to the ocean during each winter season (Table 2). The period of opening is directly related to flow conditions as well as to ocean dynamics (James, 2005; Jacobs et al., 2007). Occasional closures may occur as flows decrease near the end of the falling limb of a specific hydrograph (Appendix A), but this process is also dependent on the prevailing wet-season baseflow condition (which differs significantly from the dry season baseflow condition of ‘no flow’) and ocean dynamics. If average wet season baseflows are relatively elevated, closures are temporary, generally on the order of 2-7 days (Appendix B), but can occur multiple times a year depending on water year type and streamflow regime (Tables 1 and 2).
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Table 2. Carmel Lagoon breaching events and days open to ocean Number of artificial Number of other Wet season days Wet season days Percent of time lagoon Water Year1 breaching events2 breaching events3 open4 closed5 open to the ocean6 (days) (days) (days) (days) (%) 2012 5 4 153 21 42 2011 5 0 227 12 62 2010 6 0 224 48 61 2009 1 2 87 5 24 2008 0 2 111 3 30 2007 1 3 21 17 6 2006 1 2 151 20 41 2005 1 0 193 2 53 2004 1 3 111 9 30 2003 1 1 197 1 54 2002 2 0 177 2 48 2001 1 0 142 0 39 2000 1 0 92 8 25 1999 8 0 196 38 54 1998 2 0 267 4 73 1997 1 0 155 0 42 1996 3 0 180 4 49 1995 1 0 202 0 55 1994 1 2 35 5 10 1993 1 1 172 2 47 Summary Statistics Average 2 1 155 10 42 Median 1 0 164 5 45 Maximum 8 4 267 48 73 Minimum 0 0 21 0 6 Standard Deviation 2 1 63 13 17 Notes 1. Water Year (WY) is defined as October 1 of one year to September 30 of each subsequent year, for instance WY 2012 encompassed Oct 1, 2011 through September 30, 2012. 2. Artificial breaching eventsTable were 2 .counted Carmel as (a) Lagoon first breach breaching of the year unless events reported and otherwise, days open and (b)to when reports indicated additional mechanical breaches. 3. Other breaching events were counted when wet season lagoon closures were (a) > 1-2 days and (b) when flows were > 50 cfs prior to next opening (generally unassisted openings when later in the year) 4. Wet season days open is defined as number of days from first breach to final closure, not counting wet season days closed. 5. Wet season days closed is defined as those days when WSE remained > 11 feet (NAVD88) for longer than 24 hours. 6. Percent of time WY lagoon open to the ocean is defined as wet season days open minus wet season days closed divided by 365 days per year times 100.
In an unimpaired state, one might expect the days of open lagoon conditions to have the two following characteristics: (1) a long, sinuous outlet channel that prevents tides from rushing in and out of the lagoon and creating large WSE fluctuations that have adverse effects on water quality, and (2) a perched WSE condition in the lagoon such that the lower limit of WSE remains above the mean high tide elevation. Combined, these two states allow important fluxes (i.e. flow, sediment, salt water) to move into and out of the lagoon at a rate and intensity that is within the natural variability of the system, unlike those to which the lagoon has been subjected with sand bar management techniques of the past decades. When the conditions are such that the outlet channel is mechanically created in a pathway that would not have happened naturally and thus the lagoon is not in a perched state, the deleterious effects as enumerated in Section 4.1 and discussed in the last two paragraphs of Section 4.2
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greatly affect natural lagoon functions. The fact that the lagoon is open to the ocean on average about 40-45% of each WY (Table 2) provides an indication of the proportion of the year when open-lagoon conditions that may be negatively affected by mechanical breaching. Further, impaired open conditions need directly to impaired closed conditions, a topic of discussion in Section 4.4.
Streamflows can be large enough to fill the lagoon rapidly (see Appendix A for a visual depiction of streamflows and lagoon WSEs for each WY 1993-2000), and then depending on continuing streamflows (whether large or small, both can be drivers of openings), the outflow channel stays open or ocean forces begin to overcome riverine processes. The sand bar can remain in place for some period of time or can open up and then reform when flows are low, as it takes a longer period of time to increase lagoon volumes and WSE to the point of the next breaching. This process is illustrated most clearly in the critically dry WYs of 1994 and 2007 (Appendix A, Figures 19 and 6, respectively). In WY2007, peak flow was low and overall yearly discharge was low, so lagoon openings were limited in duration and largely dominated by ocean processes working to deposit sand and close the lagoon. A slightly different pattern can be seen in WY1994, where the peak flow was large but quite short in duration and with total yearly discharge low also, resulting in a very similar short seasonal opening pattern for the lagoon.
The ideal lagoon morphology during open conditions would be to retain a perched condition, where lagoon WSEs of greater than about 6 feet persist when mean high tides are in, providing a minimum of about 41 acre-feet of volume (Whitson Engineers, 2013b). WY2005 (Appendix A, Figure 8) is an example of the ability of the lagoon to retain a WSE of greater than 6 feet. WY2005 represents the only WY in which WSEs remained above 6 feet for the entire lagoon opening, so in 19 of 20 years, perched conditions in the lagoon were not achieved.
In WY2005, Monterey County graded an outlet channel along a “non-traditional” north- northwesterly alignment based on consultation with National Oceanic and Atmospheric Administration National Marine Fisheries Service (NMFS). The intent was that channel alignment would result in a decrease in both the rate of lagoon draw- down and a reduction in the total drop in lagoon level, thereby reducing impacts to the newly federally listed steelhead and the lagoon habitat that provides critical ecosystem functions for them. The longer more sinuous breach channel moderated flow rates and limited the total volume of lagoon draw-down. The project was a success, as lagoon WSEs maintained an extra foot or so in elevation throughout the entire lagoon open period, improving habitat quality and volume. In at least five years over the period 1993-2005, the outflow channel has been intentionally directly away
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from the north end of the beach to avoid exposing the bluff area along Scenic Drive to erosive forces (MPWMD, 2007). This type of intervention would not be necessary with the Project SRPS in place, which would be intended to provide protection from erosion to Scenic Drive and local properties that sit atop the bluff.
When a perched morphology is not maintained and WSEs dip to 5 feet, approximately 14 acre-feet of lagoon water volume remains, a 65 percent reduction in volume compared to an elevation of 6 feet associated with a perched morphology. This reduction occurs when habitat quality is likely tenuous due to large quantities of fresh water evacuating the lagoon and flowing out to the ocean. Conversely, as tides come in, the outlet channel provides a pathway for salt water ingress. When fresh water streamflows are adequate, thorough mixing of the two—fresh water and salt water— prevents stratification and provides good quality habitat (Smith, 1990). When fresh water flows are not adequate, salt water influx raises salinity concentrations to levels that juvenile steelhead may not be able to tolerate (NMFS, 2008).
Another impact of the inability of the lagoon to maintain a perched morphology due to artificial breaching is that as much as 80 percent of lagoon surface area > 3 feet in depth is flushed from the system when the sand bar breach runs directly westward (Table 3). This depth within the lagoon habitat zone is particularly important for juvenile steelhead, as they become more susceptible to predation and thermal stress in shallow waters.
The rate of lagoon draining presents additional issues for salmonids and other aquatic organisms (Table 3). Rapid evacuation of lagoon waters can force fish into shallower waters, exposing them to increased predation and potential stranding in addition to forcing out-migration of fish before they are ready for the ocean environment (Smith, 1990; NMFS, 2008; Atkinson, 2010).
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Table 3. Carmel Lagoon water surface elevations and estuary surface areas pre- and post-breaching
Table 3. Carmel Lagoon water surface elevations and estuary surface areas pre- and post-breaching WSE before Estuary surface area WSE after Estuary surface area Rate of lagoon Water Year1 breaching, NAVD882 before breaching breaching, NAVD88 after breaching3 draining (ft) (acres) (ft) (acres) (ft/hr) 2012 12.2 69.9 6.7 8.6 0.7 2011 11.8 63.8 6.7 8.6 0.2 2010 13.3 89.3 6.1 5.7 1.5 2009 13.1 86.7 6.1 5.6 2.2 2008 15.4 135.1 5.9 5.6 1.2 2007 11.5 58.3 8.8 25.3 0.3 2006 11.4 56.8 6.4 7.1 0.0 2005 13.0 85.2 7.3 12.1 0.0 2004 13.2 88.7 6.1 5.6 0.7 2003 13.6 95.1 7.1 11.3 2.1 2002 13.4 92.0 5.6 3.9 0.9 2001 14.8 120.9 5.5 3.3 2.2 2000 14.1 105.2 6.9 9.5 0.4 1999 12.8 80.0 5.0 2.1 0.4 1998 12.4 73.1 6.6 7.9 0.4 1997 12.3 72.8 8.3 20.5 0.3 1996 11.7 61.9 5.7 3.9 1.1 1995 10.5 44.8 6.4 7.0 0.1 1994 11.7 62.1 6.5 7.3 0.1 1993 12.7 79.8 6.2 6.2 0.8 Summary Statistics Average 12.7 81.1 6.5 8.4 0.8 Median 12.7 79.9 6.4 7.1 0.6 Maximum 15.4 135.1 8.8 25.3 2.2 Minimum 10.5 44.8 5.0 2.1 0.0 Standard Deviation 1.2 22.1 0.9 5.6 0.7 Notes 1. Water Year (WY) is defined as October 1 of one year to September 30 of each subsequent year, for instance WY 2012 encompassed Oct 1, 2011 through September 30, 2012. 2. First breach of the year. 3. Surface area with depth > 3 feet, suitable for steeelhead habitat.
4.4 Impaired Conditions at Lagoon Closure
Carmel Lagoon has exhibited an impaired condition at lagoon closure in at least 17 of 20 years between WYs 1993-2012 (Table 4 and 5; Appendix A) because perched lagoon morphology was not present at that time, thus impeding the development and maintenance of high quality habitat for steelhead and other species during closed conditions in the lagoon.
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NMFS and CDFW have indicated that a lagoon WSE of 6.74 NAVD88 (4 feet NGVD29) to 12.74 feet (10 feet NGVD29) is an optimal range for good quality habitat for steelhead (MPWMD, 2011), whereas in most of the recent years between WYs 1993-2012, closure WSEs have measured within the 4-foot to 5-foot range. Table 5 presents the lowest WSE prior to final season closure for these years. If the threshold of 6.74 feet is considered as the minimum WSE to qualify closure conditions as perched, then only one year, WY1998, would qualify as having closed with a perched condition. Conversations with NMFS have indicated that WY2005 exhibited a perched condition for the entire open cycle, so if that lowest WSE prior to closure would be selected as defining a perched condition, the WSE threshold would be 5.89 feet. To provide for uncertainties in WSE measures, it may be reasonable to set a WSE threshold of 5.75 feet as potentially qualifying as a perched condition at closing, although it is important to note that this value is 1 foot below the optimal range indicated by NMFS and CDFW. Using this criterion—defining 5.75 feet as lowest WSE prior to closing to constitute perched lagoon morphology—only three WYs qualify as perched: WYs 1998, 2000, and 2005.
Table 4. Carmel Lagoon final season closure dynamics Table 4. Carmel Lagoon final season closure dynamics Date of final Daily Mean Highest WSE During Lowest WSE During Time Lagoon Closed Annual Time Water Year1 seasonal closure2 Days into WY Flow at Closure Seasonal Closure Seasonal Closure in Dry Season Closed3 (date) (days) (cfs) (ft) (ft) (days) (%) 2012 5/17/2012 229 25 10.8 5.8 191 58 2011 7/20/2011 292 28 9.7 8.2 126 38 2010 7/12/2010 284 28 10.2 6.3 93 39 2009 5/18/2009 229 25 11.4 6.3 273 76 2008 4/28/2008 210 17 11.0 5.9 251 70 2007 3/20/2007 170 27 12.3 5.3 327 94 2006 6/16/2006 258 46 10.1 6.3 194 59 2005 7/12/2005 284 15 8.7 5.8 170 47 2004 4/28/2004 210 15 10.0 5.1 245 70 2003 7/1/2003 273 10 8.0 5.4 167 46 2002 5/30/2002 241 12 10.0 5.3 186 52 2001 6/1/2001 243 14 9.9 5.6 223 61 2000 5/3/2000 215 73 10.7 5.7 265 75 1999 6/24/1999 266 17 10.5 5.4 131 46 1998 9/2/1998 336 18 8.9 7.2 94 27 1997 5/12/1997 223 24 9.9 5.5 210 58 1996 6/14/1996 257 13 10.4 5.5 181 51 1995 7/29/1995 301 15 9.4 5.6 163 45 1994 3/28/1995 178 19 10.7 5.4 325 90 1993 6/25/1993 267 18 8.8 5.5 191 53 Summary Statistics Average 248 23 10.1 5.8 200 58 Median 250 18 10.1 5.6 191 55 Maximum 336 73 12.3 8.2 327 94 Minimum 170 10 8.0 5.1 93 27 Standard Deviation 42 14 1.0 0.7 66 17 Notes 1. Water Year (WY) is defined as October 1 of one year to September 30 of each subsequent year, for instance WY 2012 encompassed Oct 1, 2011 through September 30, 2012. 2. Date of final seasonal closure is the latest date in the WY on which the lagoon is no longer subject to tidal influences. 3. Annual time closed is defined as the sum of time lagooon closed in dry season plus the number of days closed in the wet season (see Table 2 also).
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Table 5. Carmel Lagoon perched morphology dynamics Date of lowest WSE before closing Lowest WSE (ft) before closing Mean daily flow (cfs) at lowest WSE before closing (date) (ft) (cfs) 5/17/2012 4.01 25 7/25/2011 4.04 26 7/12/2010 4.07 28 5/17/2009 4.10 26 4/27/2008 4.11 19 3/20/2007 4.13 27 6/14/2006 4.41 51 7/11/2005 5.89 16 4/28/2004 5.52 15 6/28/2003 5.06 13 5/29/2002 5.27 15 5/31/2001 5.00 16 4/16/2000 5.76 78 6/18/1999 5.27 26 6/9/1998 6.91 190 5/10/1997 5.59 25 6/11/1996 5.37 16 6/20/1995 5.38 85 3/28/1994 5.71 19 6/25/1993 5.56 18 Summary Statistics Average 5.1 37 Median 5.3 25 Maximum 6.9 190 Minimum 4.0 13 Standard Deviation 0.8 41
Table 5. Carmel Lagoon perched morphology dynamics Considering the three qualifying WYs more closely (see Appendix A for graphical representation), WY1998 was dominated by riverine processes very late into the spring with a mean daily flow rate of 190 cfs on the day of lowest WSE prior to closure. Flows did not cease the entire summer, so it is very likely that fresh water conditions and a mixed lagoon environment prevailed through the dry closure season. In WY2000, a late flow peak likely helped fill the lagoon with fresh water as the sand bar closed, providing a perched condition and relatively large ratio of fresh water to salt water at time of closure. Flows in this year continued into late July, so it is likely that a mixed lagoon environment prevailed through at least the beginning of the dry closure season.
What makes WY2005 notable in terms of perched conditions is that WSEs were maintained at elevated levels for the entire open condition of the WY, as well as closing at a high WSE, thus providing a much enhanced fresh water condition for steelhead through the year. This season-long condition was very likely a direct result of the lagoon outflow pathway being directed to the north, thus maintaining an elevated WSE with sand bar morphology playing a primary role in this condition.
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In an effort to address other primary water balance parameters related to hydrologic processes in the lagoon, a few points related to seepage and evaporation follow. Seepage rates from the lagoon into the barrier bar have been estimated as 8 and 12 cfs, which convert to 8 and 12 acre-feet of outflow per day if considering tides are out 50 percent of the time. These values were calculated for WY2005 and WY2009, respectively, when lagoon WSEs were on the order of 10.5 to 11.5 feet (MPWMD, 2011). The increase in seepage flow rates was conjectured to be due to artificial closure of the lagoon barrier bar at a higher elevation in WY2009, and possibly aided by additional lagoon storage capacity after the two South Arm phases of lagoon restoration were completed. Seepage rates of ocean water into the lagoon are unknown; overtopping events are the largest water influx into the lagoon in late fall (Appendix A and B).
Evaporation from the exposed areal water surface contributes to lower WSEs and potentially higher salinity concentrations. Carmel River Lagoon and the Lower Carmel Valley are classified in the evapotranspiration zone of upland central coast and Los Angeles basin in the California Irrigation Management Information System (CIMIS, 2010). Evapotranspiration rates for this zone average from a high of 6.51 inches/month in July to a low of 1.86 inches/month in January, for a total rate of 49.7 inches/year. Losses via seepage were estimated to be about 10 times greater than evaporation rates (Watson and Casagrande, 2004), so while this is a water balance output, it is relatively small.
4.5 Impaired GW-Surface Water Interactions
GW is pumped from the Lower Carmel River aquifer for consumptive uses. In past years, the shallow water aquifer has been pumped at a rate of about 11,000 acre-feet per year (PWA, 2007), while current GW withdrawals in the Lower Carmel Valley are on the order of 8,000-10,000 acre-feet per year from source areas AS3 and AS4 (MPWMD, 2011; MPWMD, 2013). AS3 and AS4 are the areas which correspond to the aquifer near the lagoon. Monitoring wells are located at three elevations within the near-shore aquifer and near the salt water-fresh water interface (Watson and Casagrande, 2004).
GW-surface water interactions are necessary to provide fresh water additions to the lagoon during closed conditions, as there are no other fresh water sources available once flows cease in the river. The ability of the aquifer to fill to a higher GW elevation is impaired if the lagoon has been mechanically breached throughout the wet season, as more fresh water is directed seaward rather than backwatering within and upstream of the lagoon, and percolating into the aquifer. Thus, the effects of breaching may lead to 2 or more feet of loss to GW elevation in the local aquifer, depending on position, and can cause the lower Carmel River surface flow to dry back and go subsurface at an earlier date. Lowered GW elevations can significantly reduce the amount of GW
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flow into the lagoon after surface flows have ceased, thus effecting summer habitat conditions. NOAA staff worked up an approximate estimate of the GW lost due to mechanical breaching from storage in the aquifer by using a storativity value (percent of water stored per unit of volume) for the local aquifer along with lower aquifer acreage and a conservative change in aquifer elevation. For Carmel Lagoon, the GW aquifer surrounding and upstream of the lagoon potentially affected by lagoon levels was approximated as 1,400 acres. The storativity value for the local aquifer was roughly estimated as 0.2, or 20% of the volume (NOAA staff pers. comm. with Martin Feeney, 2003). A 2 feet of loss in aquifer elevation in the wet season was used by NOAA as potential GW losses. Thus, NOAA developed a calculation of 1400 acres * 0.2 storativity * 2 feet in aquifer elevation loss = 560 acre-feet of potential GW loss due to mechanical breaching activities, with potentially different magnitudes of loss if any of the variables are different than this assumed set. Further, as the fresh water lens diminishes due to evaporation and seepage, a higher initial GW elevation provides a more robust fresh water supply throughout the dry summer months and into late fall and early winter until rains begin again. A more robust GW-surface water connection provides higher water quality during closed conditions.
A restoration project to create additional lagoon volume by digging out the Odello West extension of the South Arm of Carmel Lagoon uncovered a fresh water spring in the far-eastern finger of the project site (Larson et al., 2006, see Fig. 4-5, Fig. 4-6). Subsequent salinity sampling showed that a strong linear relationship exists between increases in salinity and distance from the spring. A similar linear relationship was found from the South Arm to the river channel.
Varying degrees of fresh water lens development have been documented in studies conducted in recent years (i.e. Larson et al., 2006). In Anderson et al. (see Figure 3, 2007), a longitudinal profile of salinity and other water quality parameters from data collected in late October to early November, 2007, showed that the freshest water, at an acceptable salinity concentration of 2 ppt, was found only in the far-eastern corner of the Odello West South Arm. In Castorini et al. (see Figure 8, 2008), a longitudinal profile of salinity and other water quality parameters from data collected on October 9, 2008, indicated that a fresh water lens with a salinity concentration of 2 ppt was found spread over a larger area than in 2007, extending almost to the pipe in the South Arm. In both years a small fresh water lens was detected in the far North Arm also, suggesting that GW springs may exist at both ends of the lagoon, potentially providing some measure of refugia during the dry season.
Although fresh water has been documented as present in the lagoon late in the dry season, the areas in which it is found are small, likely leading to increased competition
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between and among species for available food sources. It is quite possible that higher initial closure elevations (as was the case in WY2007 and WY2008), persistent streamflows further into the summer, and more GW inflows would result in greater volumes of fresh water throughout the dry season, creating high quality over-summer habitat by promoting growth of invertebrates that are primary steelhead food sources.
4.6 Impaired Conditions Related to Carmel Lagoon Ecosystem Health
Carmel Lagoon has been altered and modified for decades. Built infrastructure encroaches onto the lagoon floodplain as well as along much of the Carmel River corridor within the Lower Carmel Valley. The sand bar barrier between the lagoon and ocean is artificially manipulated on a consistent, yearly basis, causing evacuation of lagoon waters early in the WY. This results in tidally-open conditions that significantly increase flushing of fresh water from the system on a daily tidal basis, and closure conditions where a high ratio of highly saline ocean waters are present. Further, mechanical breaching disrupts formation of the outlet channel and sediment transport. Reestablishment of the natural beach-river transport regime is particularly important in order for sands to replenish the longshore bar to the north, which will then provide natural protection via wave energy dissipation especially during long period, large swell events. Such build-up of the longshore bar will eventually help to attenuate bluff erosion.
Upon closure, stratification of the lagoon persists until and if conversion to fresh water is achieved (NMFS, 2008). GW pumping is prevalent, extracting more water than is replenishing via infiltration and percolation into the aquifer on a yearly basis, and thus the aquifer is unable to supply as much GW inflow to the lagoon as in an unimpaired situation.
During the onset of stratified conditions, some habitat is present for juvenile steelhead in the shallow fresh water lens situated on top of the more saline lower lens. The ability of juveniles to utilize the entire water column in the lagoon is restricted by the highly saline, low dissolved oxygen, and higher temperature conditions in the lower lens. Aquatic invertebrate densities, the prey base for juvenile steelhead, are negatively correlated with increasing salinity. When conversion of a lagoon to fresh water is complete, steelhead have more abundant space and a broader prey-base leading to greater survival and growth rates (NMFS, 2008).
Steelhead run numbers are low in the Carmel River. The impact of current sand bar management activities lowers the quality of critically needed S-CCC steelhead habitat, negatively affecting the likelihood of S-CCC steelhead survival and recovery.
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Restructuring the management of the lagoon sand bar to more closely resemble the natural physical processes and hydrologic cycle of the lagoon is necessary to minimize and avoid adverse effects to critical habitat in the lagoon year-round, as well as to minimize the direct loss of S-CCC steelhead juveniles when the lagoon drains quickly to the ocean.
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5 ANTICIPATED RESPONSE OF CARMEL LAGOON TO PROJECT IMPLEMENTATION
In 2010, the MCWRA submitted an application to the USACE for a permit to manage the sand bar. In September 2011, Monterey County (RMA/Public Works) assumed a lead role for the Carmel Lagoon management. The USACE consulted with NMFS through the required section 7 consultation process under the federal ESA. During the consultation process, the NMFS affirmed that annual artificial breaching as proposed in the permit application would likely adversely affect S-CCC steelhead and destroy and adversely modify its critical habitat, and, therefore, a Jeopardy Opinion (JO) would be issued. A meeting with the NMFS and USACE to better define a solution to artificial breaching identified that the EPB and SRPS projects are viewed as their preferred projects with a means to achieving the following objectives:
• To improve the functions and values of the ecosystem in and around the Lagoon by allowing lagoon levels to rise and the lagoon to breach naturally (versus mechanically breaching the Lagoon)
• To reduce potential flood risks for existing public facilities and private structures in the low-lying developed areas located immediately to the north of, and within, the Lagoon as a result of predicted sea level rise during the next 50 years and reduction in mechanical breaching.
• To protect public infrastructure (e.g., Scenic Road embankment, State Parks restroom and parking facilities) from storm surge and scour resulting from a northerly-aligned channel.
The USACE and NMFS informed the MCWRA and County that issuance of a JO could be avoided if the application was withdrawn and a new application was filed for the EPB and SRPS projects. Therefore, the County withdrew its application for long-term sand bar management, and submitted new applications to all permitting agencies for approval of the EPB and SRPS projects, as well as a 5-year Interim Sand bar Management Plan, while the County and MCWRA completes the plans and construction of the projects. These applications were deemed incomplete pending technical studies, which are being completed as part of a feasibility study (completed June 2013) and this environmental review process.
In an effort to demonstrate the commitment to assess these projects and implement a long-term solution to mechanical breaching, the RMA worked with the USACE to develop a draft Memorandum of Understanding (MOU) that would include the USACE,
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County, and NMFS as signatory agencies. This document was reviewed by the USFWS as a consulting agency to the USACE. In September 2011, a draft MOU was completed for management of the Carmel River Lagoon. The MOU:
• Establishes a long-term plan to balance protection of private property with protection of federally listed species
• Recognizes that mechanical managing the Carmel River Lagoon over the long run was not in the best interest of the County, USACE, and NMFS’ protected resources
• Identifies two long-term solutions as alternatives to performing sand bar management: the EPB and the SRPS
• Agrees to allow an Interim Sand bar Management Plan (ISMP) for temporary (5 years) management of the sand bar while the County develops the EPB and SRPS projects (design, environmental review, and construction)
• Establishes a target schedule to complete the projects by 2018.
Because the County has managed the sand bar only under approved emergency permits, and due to the time necessary to assess the various options, the timeframe identified in the MOU for obtaining a non-emergency permit was extended to October 2013. The County is working to complete the required environmental documents consistent with the expectations of the permitting agencies. The MOU was approved by the Board of Supervisors (BOS) on June 11, 2013.
5.1 Anticipated Sand Bar Dynamics without Artificial Breaching
When river flows surpass about 30-50 cfs and remain within or above that flow range, it becomes much more likely that riverine processes are the driving mechanism of bar breaching (Rich and Keller, 2013). The tendency of breach location is likely related to the architecture of the barrier beach sand bar, sand supply, wind dynamics, and wave form and shape. The cessation of artificial breaching will allow for a more natural sediment transport regime. This would be manifest when the annual cycles of barrier bar building and opening experience more of the natural dynamics associated with river outflow, tides, wave action, cross-shore, and littoral and longshore transport (Moffatt and Nichol, 2013; J. Pearson-Meyers, pers. comm., 2013).
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5.2 Anticipated Lagoon Morphology
Breach outflow channel width and depth are primarily a function of wave and littoral transport processes as well as inflow rate and lagoon volume prior to opening, so affects naturally-occurring channel widths and depths would vary according to ocean and flow conditions. Data from WY2005 indicates that perched lagoon morphology will occur in Carmel Lagoon when the outflow channel runs to the north (Appendix A, Figure 8). There is a tendency for outflows to migrate north, as determined in WYs 1993, 1996, 1997, and 2000 by Thornton’s (2005) littoral processes study of existing data and aerial photos, and in 2005 as reported by MPWMD (2007). It is expected that a northerly route will likely develop more often than currently occurs once artificial breaching ceases. A natural channel might form to the south in some years, as outlet formation is dependent on the longshore current. Ocean wave patterns can change in some years, although an outlet channel to the south should occur with a lower frequency than to the north.
NMFS and CDFW have indicated that a lagoon WSE in the range of 6.74 to 12.74 feet NAVD88 (4 to 10 feet NGVD29) is an optimal range for steelhead (MPWMD, 2011) while a threshold value of 5.75 feet was used in Table 5 to assess the probability of perched conditions in recent years. Conditions in WY2005 provide evidence of a perched morphology that would promote a WSE that might be achieved regularly with a northerly configuration to the outflow channel. The northern beach has smaller sand grain-sizes and a lower slope than the southern portion of the beach (Moffat and Nichol, 2013), while longshore currents tend to carry sand to the north due to diffraction of waves around Steward’s Cove (Thornton, 2005). Slopes on the northern portion of the beach are much lower than those on the south end of the beach: 12 percent versus 28 percent, respectively (Thornton, 2005). These observations provide an indication of why the lagoon outlet might tend to migrate to the north, as there may be less resistance in the architecture of smaller grain sizes, and the lower slopes may provide a path of least resistance to the ocean.
When higher WSEs prevail in the lagoon over the course of an open-lagoon winter season, the lagoon WSE should remain high upon closure and with a higher ratio of fresh water because tidal inflow cannot negotiate the sinuous outflow pathway easily, thus less salt water will enter and remain in the lagoon (J. Pearson-Meyers, pers. comm., 2013).
5.3 Anticipated Conditions at Lagoon Closure
Carmel Lagoon geology includes a bedrock sill at the northern and southern ends of the river mouth. This sill may play a role in maintaining lagoon WSE, particularly when the
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outflow path is oriented to the north and a long and sinuous channel can form. Meandering outflow channels that flow across this bedrock sill, such as in Carmel Lagoon in water year 2005, are able to retain higher WSEs in the lagoon.
The higher WSE and continuing inflows until those dry up should provide a perched, fresh water lagoon at the beginning of the summer dry season that will remain as a fresh water system throughout the closure season and year-round.
5.4 Anticipated GW-Surface Water Interactions
There are a number of projects in progress associated with the Lower Carmel River and Lagoon, including Odello East floodplain restoration, retrofit of San Clemente Dam in the upper watershed, and GW infiltration into the floodplain aquifer on the Odello West floodplain area of the lower watershed at the lagoon (PWA, 2007). These projects will likely have effects on the Lagoon and its interaction with streamflow and local GW, and should provide net positive benefits to lagoon ecosystem health.
5.5 Anticipated Ecosystem Effects
The purpose of Project implementation is to restore the natural function of the lagoon by reducing the necessity to artificially breach the sand bar. Anticipated ecosystem effects should subsequently help restore the natural function of the lagoon and protect surrounding infrastructure. These effects include (1) more natural breaching cycles, (2) increased WSE in the lagoon while open in a northerly direction, (3) a higher ratio of fresh water to salt water, (4) conversion of the lagoon into a fresh water system during closure via the higher ratio of fresh water and streamflow prior to drying up in the summer, and (5) greater connectivity between the lagoon and the local GW. A return to naturally functioning lagoon ecosystem conditions should allow for steelhead and other aquatic and terrestrial species to thrive within a highly productive lagoon ecosystem.
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Anderson, T., Clark, C., Croyle, Z., Maas-Baldwin, J., Urquhart, K., and Watson, F., 2007, Carmel lagoon water quality and steelhead soundings: Fall 2007, a report from the Central Coast Watershed Studies Team (CCoWS), The Watershed Institute, CSU-Monterey Bay, WI-2007-04, 26 p. Accessed on July 30, 2013 at http://ccows.csumb.edu/pubs/.
Atkinson, K.A., 2010, Habitat conditions and steelhead abundance and growth in a California lagoon, Master’s thesis, San Jose State University, 123 p.
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Casagrande, J., Watson, F., Anderson, T., and Newman, W., 2002, Hydrology and water quality of the Carmel and Salinas Lagoons, Monterey Bay, California 2001/2002, a report from the Central Coast Watershed Studies Team (CCoWS), The Watershed Institute, CSU-Monterey Bay, WI-2002-04, 111 p. Accessed on July 30, 2013 at http://ccows.csumb.edu/pubs/.
Coates, M.J., and Guo, Y, 2003, The salt wedge position in a bar-clocked estuary subject to pulsed inflows, Estuarine, Coastal and Shelf Science, 58: 187-196.
County of Monterey, U.S. Army Corps of Engineers, and National Marine Fisheries Service (CL- MOU-2012), 2012, (Draft) Flood prevention and habitat protection at the Carmel Lagoon, Memorandum of Understanding, 20 p.
Debler, W., and Imberger, J., 1996, Flushing criteria in estuarine and laboratory experiments, Journal of Hydraulic Engineering, Vol. 122, No. 12, p. 728-734.
Feeney, M., 2003, personal communication with NMFS personnel.
Hampson, L., 2013, Monterey Peninsula Water Management District personnel, personal communications.
Hayes, S.A., Bond, M.H., Hanson, C.V., Freund, E.V., Smith, J.J., Anderson, E.C., Ammann, A.J., and MacFarlane, R.B., 2008, Steelhead growth in a small Central California watershed: upstream and estuarine rearing patterns, Transactions of the American Fisheries Society, 137: 114-128. DOI: 10.1577/T07-043.1.
Jacobs, D.K., Stein, E.D., and Longcore, T., 2011, Classification of California estuaries based on natural closure patterns: templates for restoration and management: technical report 619.a prepared for Southern California Coastal Water Research Project, 72 p.
James, G.W., 2005, Surface water dynamics at the Carmel River lagoon, water years 1991 through 2005, Monterey Peninsula Water Management District, 152 p.
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James, G.W., 2013, Monterey Peninsula Water Management District personnel, personal communications.
Johnson, T., 2007, Battling seawater intrusion in the Central and West Coast Basins, Technical bulletin 13, Water replenishment district of Southern California, p. 2. Accessed on September 29, 2013 at http://www.wrd.org/engineering/reports/TB13_Fall07_Seawater_Barriers.pdf.
Larson, J., Watson, F., Casagrande, J., and Pierce, B., 2006, Carmel River Lagoon enhancement project: water quality and aquatic wildlife monitoring 2005-06, a report from the Central Coast Watershed Studies Team (CCoWS), The Watershed Institute, CSU-Monterey Bay, 102 p. Accessed on July 30, 2013 at http://ccows.csumb.edu/pubs/.
Larson, J., Watson, F,. Masek, J., Watts, M., Casagrande, J., 2005, Carmel River Lagoon enhancement project: water quality and aquatic wildlife monitoring 2004-05, report to California Department of Parks and Recreation from the Central Coast Watershed Studies Team (CCoWS), The Watershed Institute, CSU-Monterey Bay, 134 p. Accessed on July 30, 2013 at http://ccows.csumb.edu/pubs/.
Moffatt and Nichol, 2013, Carmel River Lagoon Biological Assessment, Coastal Engineering Analysis: Draft report prepared for Monterey County Department of Public Works, 21 p.
Monterey Peninsula Water Management District (MPWMD), 2013, 2010-2011 annual report for the MPWMD mitigation program, 170 p. Accessed on July 25, 2013 at http://www.mpwmd.net/programs/mitigation_program/annual_report/annual_reportrev1.ht m.
Monterey Peninsula Water Management District (MPWMD), 2011, 2009-2010 annual report for the MPWMD mitigation program, 161 p. Accessed on July 25, 2013 at http://www.mpwmd.net/programs/mitigation_program/annual_report/annual_reportrev1.ht m.
Monterey Peninsula Water Management District (MPWMD), 2007, Study plan for long term adaptive management of the Carmel River State Beach and Lagoon, 40 p. Accessed on September 25, 2013 at http://www.mpwmd.dst.ca.us/Mbay_IRWM/IRWM_library/CarmelBay/LongTermStudyPlanFin al2007-04-17.pdf
National Marine Fisheries Service (NMFS), 2008, Biological Opinion for water supply, flood control operations, and channel maintenance conducted by the US Army Corps of Engineers, the Sonoma County Water Agency, and the Mendocino County Russian River Flood Control and Water Conservations Improvement District in the Russian River watershed, F/SWR/2006/07316, 386 p.
Philip Williams and Associates, Ltd., and Ecosystem Management International (PWA), 2007, Supplemental Carmel River watershed action plan, prepared for the Planning and Conservation League Foundation in partnership with the Carmel River Watershed Conservancy, p. 106.
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Smith, J.J., 1990, the effects of sand bar formation and inflows on aquatic habitat and fish utilization in Pescadero, San Gregorio, Waddell and Pomponio Creek estuary/lagoon
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systems, 1985-1989. Report prepared under Interagency Agreement 84-04-324, between Trustees for California State University and the California Department of Parks and Recreation, 47 p. + 4 tables and 52 figures.
Thornton, E.B., 2005, Littoral processes and river breachings at Carmel River Beach, prepared for the Monterey Peninsula Water Management District,12 p.
Urquhart, K.U., 2013, Carmel River fisheries reports for water year 2012 and October through December water year 2013, Monterey Peninsula Water Management District, 34 p.
Van Dyke, E., and Wasson, K., 2005, Historical ecology of a Central California estuary: 150 years of habitat change, Estuaries, Vol. 28, No. 2, p. 173-189.
Watson, F., Newman, W., Anderson, T., Alexander, S., Kozlowski, D., 2001, Winter water quality of the Carmel and Salinas Lagoons, Monterey Bay, California 2000/2001, a report from the Central Coast Watershed Studies Team (CCoWS), The Watershed Institute, CSU-Monterey Bay, WI-2001-01, 42 p. Accessed on July 30, 2013 at http://ccows.csumb.edu/pubs/.
Watson F., and Casagrande, J., 2004, Potential effects of GW extractions on Carmel Lagoon, a report from the Central Coast Watershed Studies Team (CCoWS), The Watershed Institute, CSU-Monterey Bay, WI-2001-01, 42 p.
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APPENDICES
APPENDIX A
Water surface elevations in Carmel Lagoon and streamflow in Carmel River at Highway 1 gage, WYs 1993-2012
15 500 Lagoon WSE 450 Carmel River discharge 13 400
11
NAVD88) 350
(feet,
300 9 (cfs)
250 Elevation
7 Discharge
200 Water
Mean 150
Mean 5
Daily
Daily 100 3 50
1 0 3/8/12 7/6/12 9/30/11 11/9/11 1/28/12 4/17/12 5/27/12 8/15/12 9/24/12 12/19/11
Figure 1. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2012, Monterey County, California. Sources: Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River discharge 13 400
11
NAVD88) 350
(feet,
300 9 (cfs)
250 Elevation
7 Discharge
200 Water
Mean 150
Mean 5
Daily
Daily 100 3 50
1 0 7/8/11 10/1/10 1/29/11 3/10/11 4/19/11 5/29/11 8/17/11 9/26/11 11/10/10 12/20/10
Figure 2. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2011, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/10 10/1/09 1/29/10 3/10/10 4/19/10 5/29/10 8/17/10 9/26/10 11/10/09 12/20/09
Figure 3. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2010, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/09 10/1/08 1/29/09 3/10/09 4/19/09 5/29/09 8/17/09 9/26/09 11/10/08 12/20/08
Figure 4. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2009, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 3/9/08 7/7/08 10/1/07 1/29/08 4/18/08 5/28/08 8/16/08 9/25/08 11/10/07 12/20/07
Figure 5. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2008, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/07 10/1/06 1/29/07 3/10/07 4/19/07 5/29/07 8/17/07 9/26/07 11/10/06 12/20/06
Figure 6. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2007, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/06 10/1/05 1/29/06 3/10/06 4/19/06 5/29/06 8/17/06 9/26/06 11/10/05 12/20/05
Figure 7. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2006, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/05 10/1/04 1/29/05 3/10/05 4/19/05 5/29/05 8/17/05 9/26/05 11/10/04 12/20/04
Figure 8. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2005, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 3/9/04 7/7/04 10/1/03 1/29/04 4/18/04 5/28/04 8/16/04 9/25/04 11/10/03 12/20/03
Figure 9. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2004, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/03 10/1/02 1/29/03 3/10/03 4/19/03 5/29/03 8/17/03 9/26/03 11/10/02 12/20/02
Figure 10. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2003, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/02 10/1/01 1/29/02 3/10/02 4/19/02 5/29/02 8/17/02 9/26/02 11/10/01 12/20/01
Figure 11. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2002, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/01 10/1/00 1/29/01 3/10/01 4/19/01 5/29/01 8/17/01 9/26/01 11/10/00 12/20/00
Figure 12. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2001, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 3/9/00 7/7/00 10/1/99 1/29/00 4/18/00 5/28/00 8/16/00 9/25/00 11/10/99 12/20/99
Figure 13. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 2000, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/99 10/1/98 1/29/99 3/10/99 4/19/99 5/29/99 8/17/99 9/26/99 11/10/98 12/20/98
Figure 14. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1999, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/98 10/1/97 1/29/98 3/10/98 4/19/98 5/29/98 8/17/98 9/26/98 11/10/97 12/20/97
Figure 15. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1998, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/97 10/1/96 1/29/97 3/10/97 4/19/97 5/29/97 8/17/97 9/26/97 11/10/96 12/20/96
Figure 16. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1997, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 3/9/96 7/7/96 10/1/95 1/29/96 4/18/96 5/28/96 8/16/96 9/25/96 11/10/95 12/20/95
Figure 17. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1996, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 15‐min data 450 Carmel River daily mean 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/95 10/1/94 1/29/95 3/10/95 4/19/95 5/29/95 8/17/95 9/26/95 11/10/94 12/20/94
Figure 18. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1995, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 30‐min data 450 Lagoon WSE 15‐min data 13 Carmel River 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/94 10/1/93 1/29/94 3/10/94 4/19/94 5/29/94 8/17/94 9/26/94 11/10/93 12/20/93
Figure 19. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1994, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication. 15 500 Lagoon WSE 30‐min data 450 Carmel River 13 400
11
NAVD88) 350
(cfs)
(feet,
300 9
250 Discharge
Elevation
7 Daily 200 Water
150 Mean
Mean 5
Daily 100 3 50
1 0 7/8/93 10/1/92 1/29/93 3/10/93 4/19/93 5/29/93 8/17/93 9/26/93 11/10/92 12/20/92
Figure 20. Water level in Carmel River Lagoon at south arm gage and flow in Carmel River at Highway 1 gage, water year 1993, Monterey County, California. Monterey Peninsula Water Management District raw lagoon water surface elevation datalogger files are provisional and subject to revision. USGS 11143250 daily mean discharge data are approved for publication.
APPENDIX B
Compilation tables of riverine dynamics of breaches and closures, WYs 1993-2012
Table 1. WY 2012, Riverine Dynamics of Breaches and Closures Temporary Temporary Temporary Temporary Temporary WSE increase while Sustained closure breach breach In‐season closure breach breach In‐season closure Sustained breach* In‐season closure breach In‐season closure Sustained breach In‐season closure Sustained breach In‐season closure Sustained breach Early closure Final Closure closed Breach Type Mechnical, Natural, or Unknown Mechanical Mechanical Mechanical Mechanical Mechanical Natural Natural Natural Natural Mechanical Mechanical Dry Season Events 10/1/2011 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/3/2011 15:30 Lowest lagoon WSE during closure, this WY 9.95 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach Date‐Time of lowest WSE prior to significant increase in WSE 9/21/12 9:15 WSE (ft) 5.78 Date‐Time of highest WSE post‐increase 9/24/12 21:15 WSE (ft) 8.36 Increase in WSE (ft) 2.58 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0 Date‐Time of most recent WSE > 11 ft prior to breach, this WY 11/16/2011 20:15 Time (days) between start of WY and first seasonal breach 46.8 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 11/16/2011 20:15 11/25/2011 17:45 12/20/2011 16:00 1/17/2012 11:30 1/22/2012 17:30 2/6/2012 18:30 2/20/2012 14:30 3/3/2012 17:30 3/18/2012 13:30 WSE (ft) 12.43 12.62 12.66 12.74 12.17 11.43 13.01 11.89 12.79 Date‐Time of lowest WSE directly following breach 11/19/2011 13:30 11/27/2011 15:30 12/23/2011 15:00 1/18/2012 18:15 1/23/2012 1:30 2/7/2012 9:15 2/21/2012 5:30 3/4/2012 0:15 3/18/2012 17:15 WSE (ft) 12.19 9.45 11.38 9.64 6.69 9.24 4.24 4.00 4.03 WSE pre‐breach minus post‐breach (ft) 0.23 3.17 1.28 3.10 5.47 2.19 8.77 7.88 8.76 Time difference (days) 2.72 1.91 2.96 1.28 0.33 0.61 0.63 0.28 0.16 Time difference (hours) 65.25 45.75 71.00 30.75 8.00 14.75 15.00 6.75 3.75 Rate of WSE decline (ft/hr) 0.00 0.07 0.02 0.10 0.68 0.15 0.58 1.17 2.34 Mean daily flow rate (cfs) on day of breach 16 18 17 11 39 25 20 38 96 Mean daily flow rate (cfs) on day of lowest WSE following breach 17 17 15 12 39 24 20 30 96 Likely mechanism with greatest influence on breaching process Mechanical Mechanical Mechanical Mechanical Mechanical/Riverine Mechanical Unknown Riverine Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 11/27/2011 15:30 1/18/2012 18:30 2/2/2012 3:15 2/7/2012 9:45 2/21/2012 5:30 3/4/2012 18:45 WSE (ft) 9.45 9.64 7.43 9.23 4.24 3.99 Date‐Time of lagoon WSE fills to > 11 feet 12/3/2011 13:00 1/21/2012 17:45 2/5/2012 11:15 2/9/2012 10:00 2/29/2012 16:30 3/14/2012 11:00 WSE (ft) 11.00 11.00 11.00 11.00 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 1/18/2012 9:00 1/22/2012 21:30 2/6/2012 22:30 2/20/2012 20:45 3/3/2012 18:30 3/18/2012 14:30 WSE (ft) 10.97 10.83 10.99 10.93 10.85 9.76 Time (days) of WSE > 11 feet 45.83 1.16 1.47 11.45 3.08 4.15 Time (hours) of WSE > 11 feet 1100.0 27.8 35.3 274.8 74.0 99.5 Mean daily flow rate (cfs) on day lowest WSE 17 12 33 24 20 30 Mean daily flow rate (cfs) on day WSE > 11 feet 15 27 27 22 17 15 Mean daily flow rate (cfs) on day WSE < 11 feet 12 39 25 20 38 96 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Ocean Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 5/15/2012 1:15 6/7/2012 2:15 WSE (ft) 10.80 10.77 Date‐Time of lowest WSE during WY closure 5/15/2012 16:15 9/20/2012 13:00 WSE (ft) 4.02 5.77 Time (days) difference highest minus lowest WSE 0.63 105.45 Time (hours) difference highest minus lowest WSE 15.00 2530.75 Highest WSE at closure minus lowest WSE during closure in this WY 6.77 5.00 Rate of decrease in WSE (ft/day) 0.452 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 27 27 Mean daily flow rate (cfs) on day of lowest WSE of dry season n/a 0 Likely mechanism with greatest influence on process Mechanical Ocean End of WY 9/30/2012 23:45 Time (days) between final season closure and end of WY 115.9 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 162.7 Totel days of closure including all partial closures 184.0 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as temporary lagoon closing due to mechanical or ocean processes approximately 1 month to 1 week before than final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included the sum of days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in the MPWMD WY 2012 fisheries report (Urquhart, 2013) Table 2. WY 2011, Riverine Dynamics of Breaches and Closures Temporary Temporary Sustained closure breach In‐season closure breach In‐season closure Sustained breach* In‐season closure Sustained breach In‐season closure Sustained breach Final Closure Breach Type Natural, Mechanical or Unknown Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Dry Season Events 10/1/2010 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/21/2010 8:15 Lowest lagoon WSE during closure, this WY 7.89 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach Date‐Time of lowest WSE prior to significant increase in WSE WSE (ft) Date‐Time of highest WSE post‐increase WSE (ft) Increase in WSE (ft) Likely mechanism with greatest influence on WSE increase process Mean daily flow rate (cfs) on day of highest WSE Date‐Time of most recent WSE > 11 ft prior to breach, this WY 11/24/2010 16:00 Time (days) between start of WY and first seasonal breach 54.7 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 11/24/2010 16:00 12/9/2010 15:15 12/16/2010 20:45 1/29/2011 0:15 2/14/2011 17:45 WSE (ft) 11.63 11.89 11.80 12.18 12.01 Date‐Time of lowest WSE directly following breach 11/26/2010 9:30 12/10/2010 1:30 12/18/2010 3:30 1/29/2011 3:30 2/14/2011 21:15 WSE (ft) 9.46 9.66 6.69 4.97 5.30 WSE pre‐breach minus post‐breach (ft) 2.16 2.22 5.11 7.21 6.71 Time difference (days) 1.73 0.43 1.28 0.14 0.15 Time difference (hours) 41.50 10.25 30.75 3.25 3.50 Rate of WSE decline (ft/hr) 0.05 0.22 0.17 2.22 1.92 Mean daily flow rate (cfs) on day of breach 19 15 17 51 21 Mean daily flow rate (cfs) on day of lowest WSE following breach 17 15 16 51 21 Likely mechanism with greatest influence on breaching process Mechanical Mechanical Mechanical Riverine Mechanical Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 11/26/2010 9:30 12/10/2010 1:30 1/26/2011 14:15 2/3/2011 5:30 WSE (ft) 9.46 9.66 4.63 5.13 Date‐Time of lagoon WSE fills to > 11 feet 12/3/2010 0:45 12/13/2010 14:15 1/27/2011 21:00 2/13/2011 6:00 WSE (ft) 11.00 11.00 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 12/9/2010 21:45 12/16/2010 22:15 1/29/2011 1:15 2/14/2011 19:30 WSE (ft) 10.99 10.94 10.48 10.70 Time (days) of WSE > 11 feet 6.88 3.33 1.18 1.56 Time (hours) of WSE > 11 feet 165.0 80.0 28.3 37.5 Mean daily flow rate (cfs) on day lowest WSE 18 22 67 61 Mean daily flow rate (cfs) on day WSE > 11 feet 15 17 64 21 Mean daily flow rate (cfs) on day WSE < 11 feet 15 17 51 21 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Unknown Dry Season Closure Date‐Time of highest WSE at WY closure 8/11/2011 1:45 WSE (ft) 9.69 Date‐Time of lowest WSE during WY closure 9/8/2011 12:00 WSE (ft) 8.20 Time (days) difference highest minus lowest WSE 28.43 Time (hours) difference highest minus lowest WSE 682.25 Highest WSE at closure minus lowest WSE during closure in this WY 1.48 Rate of decrease in WSE (ft/day) 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 13 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2011 23:45 Time (days) between final season closure and end of WY 50.9 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 105.6 Totel days of closure including all partial closures 118.5 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in MPWMD, 2010‐2011 annual mitigation report Table 3. WY 2010, Riverine Dynamics of Breaches and Closures Temporary In‐season Sustained closure Sustained breach* In‐season closure Sustained breach In‐season closure breach In‐season closure Sustained breach In‐season closure Sustained breach closure Sustained breach Final Closure Breach Type Natural, Mechanical or Unknown Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Natural Dry Season Events 10/1/2009 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/12/2009 5:00 Lowest lagoon WSE during closure, this WY Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach Date‐Time of lowest WSE prior to significant increase in WSE ‐‐ WSE (ft) Date‐Time of highest WSE post‐increase WSE (ft) Increase in WSE (ft) Likely mechanism with greatest influence on WSE increase process Mean daily flow rate (cfs) on day of highest WSE Date‐Time of most recent WSE > 11 ft prior to breach, this WY 10/14/2009 9:45 Time (days) between start of WY and first seasonal breach 13.4 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 10/14/2009 9:45 11/7/2009 15:30 12/7/2009 0:15 12/13/2009 10:15 12/31/2009 14:30 1/12/2010 14:45 WSE (ft) 13.25 12.44 12.85 12.21 12.48 12.65 Date‐Time of lowest WSE directly following breach 10/14/2009 14:30 11/7/2009 22:15 12/9/2009 2:30 12/14/2009 3:15 12/31/2009 22:15 1/13/2010 20:00 WSE (ft) 6.10 4.32 10.21 5.88 4.24 4.95 WSE pre‐breach minus post‐breach (ft) 7.15 8.12 2.64 6.33 8.24 7.69 Time difference (days) 0.20 0.28 2.09 0.71 0.32 1.22 Time difference (hours) 4.75 6.75 50.25 17.00 7.75 29.25 Rate of WSE decline (ft/hr) 1.51 1.20 0.05 0.37 1.06 0.26 Mean daily flow rate (cfs) on day of breach 759 18 20 182 47 40 Mean daily flow rate (cfs) on day of lowest WSE following breach 759 18 22 202 47 42 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Mechanical Mechanical Mechanical/Riverine Riverine Unknown Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 10/20/2009 6:00 11/7/2009 22:15 12/9/2009 4:00 12/24/2009 1:30 1/7/2010 0:30 WSE (ft) 4.78 4.32 10.21 5.01 4.35 Date‐Time of lagoon WSE fills to > 11 feet 10/22/2009 20:15 11/17/2009 14:15 12/10/2009 9:45 12/27/2009 5:00 1/9/2010 22:15 WSE (ft) 11.00 11.00 11.00 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 11/7/2009 18:15 12/8/2009 7:00 12/13/2009 18:15 12/31/2009 17:30 1/13/2010 6:00 WSE (ft) 10.39 10.98 10.44 10.42 10.79 Time (days) of WSE > 11 feet 15.92 20.70 3.35 4.52 3.32 Time (hours) of WSE > 11 feet 382.0 496.7 80.5 108.5 79.7 Mean daily flow rate (cfs) on day lowest WSE 51 18 22 55 41 Mean daily flow rate (cfs) on day WSE > 11 feet 37 18 21 48 38 Mean daily flow rate (cfs) on day WSE < 11 feet 18 22 182 47 42 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Unknown Unknown Dry Season Closure Date‐Time of highest WSE at WY closure 7/25/2010 2:45 WSE (ft) 10.21 Date‐Time of lowest WSE during WY closure 9/23/2010 19:00 WSE (ft) 6.34 Time (days) difference highest minus lowest WSE 60.68 Time (hours) difference highest minus lowest WSE 1456.25 Highest WSE at closure minus lowest WSE during closure in this WY 3.86 Rate of decrease in WSE (ft/day) 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 18 Mean daily flow rate (cfs) on day of lowest WSE of dry season 2.3 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2010 23:45 Time (days) between final season closure and end of WY 67.9 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 81.3 Totel days of closure including all partial closures 129.1 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in MPWMD, 2009‐2010 annual mitigation report Table 4. WY 2009, Riverine Dynamics of Breaches and Closures Sustained In‐season Sustained In‐season Sustained WSE increase closure Sustained breach* closure breach closure breach Final closure while closed Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Natural Dry Season Events 10/1/2008 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/1/2008 0:15 Lowest lagoon WSE prior to breach, in current WY 6.59 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach Date‐Time of lowest WSE directly prior to overtopping ‐‐ 9/11/2009 11:15 WSE (ft) 6.44 Date‐Time of highest WSE post‐wave overtopping 9/12/2009 18:45 WSE (ft) 8.34 Increase in WSE (ft) 1.90 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE Date‐Time of most recent WSE > 11 ft prior to breach, in current WY none Time (days) between start of WY and first seasonal breach 138.6 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 2/16/2009 13:30 4/9/2009 3:15 5/9/2009 7:30 WSE (ft) 13.11 12.76 12.15 Date‐Time of lowest WSE directly following breach 2/16/2009 16:45 4/9/2009 9:45 5/9/2009 18:45 WSE (ft) 6.08 4.71 4.15 WSE pre‐breach minus post‐breach (ft) 7.03 8.05 7.99 Time difference (days) 0.14 0.27 0.47 Time difference (hours) 3.25 6.50 11.25 Rate of WSE decline (ft/hr) 2.16 1.24 0.71 Mean daily flow rate (cfs) on day of breach 749 91 38 Mean daily flow rate (cfs) on day of lowest WSE following breach 749 91 38 Likely mechanism with greatest influence on process Mechanical/Riverine Riverine Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet 4/5/2009 18:00 5/3/2009 16:00 WSE (ft) 4.53 4.11 Date‐Time of lagoon WSE fills to > 11 feet 4/7/2009 16:15 5/6/2009 14:45 WSE (ft) 11.00 11.01 Date‐Time of lagoon falls below WSE > 11 feet 4/9/2009 4:00 5/9/2009 8:00 WSE (ft) 11.44 11.95 Time (days) of WSE > 11 feet 1.5 2.7 Time (hours) of WSE > 11 feet 35.75 65.25 Mean daily flow rate (cfs) on day lowest WSE 79 57 Mean daily flow rate (cfs) on day WSE > 11 feet 74 45 Mean daily flow rate (cfs) on day WSE < 11 feet 91 38 Likely mechanism with greatest influence on process Ocean Ocean Dry Season Closure Date‐Time of highest WSE at final WY closure 6/10/2009 4:15 WSE (ft) 11.37 Date‐Time of lowest WSE during WY closure 8/21/2009 12:15 WSE (ft) 6.30 Time (days) difference highest minus lowest WSE 72.3 Time (hours) difference highest minus lowest WSE 1736 Highest WSE at closure minus lowest WSE during closure in this WY 5.07 Rate of decrease in WSE (ft/day) 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 16 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2009 23:45 Time (days) between final season closure and end of WY 112.8 Total days of lagoon closure, from previous WY closure to this WY 1st breach 251.4 Totel days of closure including all partial closures 255.6 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in MPWMD, 2008‐2009 annual mitigation report Table 5. WY 2008, Riverine Dynamics of Breaches and Closures Sustained WSE increase while Sustained closure closed breach* In‐season closure Sustained breach Final closure Breach Type Mechnical, Natural, or Unknown Natural Natural Natural Dry Season Events 10/1/2007 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/1/2007 10:00 Lowest lagoon WSE during closure, this WY 6.04 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE directly prior to significant overtopping 12/3/2007 16:00 WSE (ft) 7.41 Date‐Time of highest WSE post‐wave overtopping 12/5/2007 10:15 WSE (ft) 8.66 Increase in WSE (ft) 1.25 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0 Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 96.0 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 1/5/2008 9:15 4/22/2008 20:30 WSE (ft) 15.40 11.71 Date‐Time of lowest WSE directly following breach 1/5/2008 17:30 4/23/2008 9:30 WSE (ft) 5.85 4.26 WSE pre‐breach minus post‐breach (ft) 9.55 7.44 Time difference (days) 0.34 0.54 Time difference (hours) 8.25 13.00 Rate of WSE decline (ft/hr) 1.16 0.57 Mean daily flow rate (cfs) on day of breach 509 21 Mean daily flow rate (cfs) on day of lowest WSE following breach 509 22 Likely mechanism with greatest influence on process Riverine Unknown Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 4/13/2008 16:00 WSE (ft) 4.19 Date‐Time of lagoon WSE fills to > 11 feet 4/19/2008 18:45 WSE (ft) 11.00 Date‐Time of lagoon falls below WSE > 11 feet 4/22/2008 21:45 WSE (ft) 10.99 Time (days) of WSE > 11 feet 3.1 Time (hours) of WSE > 11 feet 75.00 Mean daily flow rate (cfs) on day lowest WSE 33 Mean daily flow rate (cfs) on day WSE > 11 feet 21 Mean daily flow rate (cfs) on day WSE < 11 feet 21 Likely mechanism with greatest influence on process Ocean Dry Season Closure Date‐Time of highest WSE at final WY closure 5/13/2008 22:30 WSE (ft) 10.96 Date‐Time of lowest WSE during WY closure 8/10/2008 6:45 WSE (ft) 5.87 Time (days) difference highest minus lowest WSE 88.34 Time (hours) difference highest minus lowest WSE 2120.25 Highest WSE at closure minus lowest WSE during closure in this WY 5.09 Rate of decrease in WSE (ft/day) 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 11 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2008 23:45 Time (days) between final season closure and end of WY 140.1 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 236.0 Totel days of closure including all partial closures 239.1 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in MPWMD 2007‐2008 annual mitigation report Table 6. WY 2007, Riverine Dynamics of Breaches and Closures Sustained WSE increase while WSE increase Temporary Sustained Temporary closure closed while closed breach In‐season closure Temporary breach In‐season closure breach* In‐season closure breach Early closure Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Natural Natural Natural Dry Season Events 10/1/2006 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/12/2006 3:45 Lowest lagoon WSE during closure, this WY 6.61 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 12/5/2006 23:45 1/10/2007 20:45 WSE (ft) 7.56 8.43 Date‐Time of highest WSE post‐increase 12/10/2006 16:00 2/11/2007 10:30 WSE (ft) 9.06 11.45 Increase in WSE (ft) 1.51 3.02 Likely mechanism with greatest influence on WSE increase process Wave overtopping Riverine Mean daily flow rate (cfs) on day of highest WSE 0 Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 133.4 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 2/11/2007 10:30 2/19/2007 14:30 2/25/2007 10:45 3/18/07 22:45 WSE (ft) 11.45 11.72 11.92 11.57 Date‐Time of lowest WSE directly following breach 2/15/2007 6:30 2/21/2007 12:00 2/25/2007 19:30 3/19/07 9:15 WSE (ft) 8.84 6.61 8.92 4.42 WSE pre‐breach minus post‐breach (ft) 2.62 5.11 3.01 7.15 Time difference (days) 3.83 1.90 0.36 0.44 Time difference (hours) 92.00 45.50 8.75 10.50 Rate of WSE decline (ft/hr) 0.03 0.11 0.34 0.68 Mean daily flow rate (cfs) on day of breach 29 32 45 30 Mean daily flow rate (cfs) on day of lowest WSE following breach 50 28 45 28 Likely mechanism with greatest influence on breaching process Mechanical Unknown Riverine Ocean Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 2/16/2007 7:30 2/20/2007 22:30 3/12/2007 20:15 WSE (ft) 8.86 7.05 4.67 Date‐Time of lagoon WSE fills to > 11 feet 2/18/2007 8:30 2/24/2007 3:00 3/17/2007 8:30 WSE (ft) 11.01 11.00 11.01 Date‐Time of lagoon falls below WSE > 11 feet 2/19/2007 16:15 2/25/2007 13:30 3/19/2007 0:00 WSE (ft) 10.89 10.91 10.93 Time (days) of WSE > 11 feet 1.3 1.4 1.6 Time (hours) of WSE > 11 feet 31.75 34.50 39.50 Mean daily flow rate (cfs) on day lowest WSE 44 29 47 Mean daily flow rate (cfs) on day WSE > 11 feet 36 46 32 Mean daily flow rate (cfs) on day WSE < 11 feet 32 45 28 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 3/27/2007 3:45 4/26/2007 22:45 WSE (ft) 11.30 12.25 Date‐Time of lowest WSE during WY closure 4/8/2007 0:15 8/20/2007 11:45 WSE (ft) 10.07 5.25 Time (days) difference highest minus lowest WSE 11.85 115.54 Time (hours) difference highest minus lowest WSE 284.50 2773.00 Highest WSE at closure minus lowest WSE during closure in this WY 1.24 7.01 Rate of decrease in WSE (ft/day) 0.004 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 25 17 Mean daily flow rate (cfs) on day of lowest WSE of dry season 14 0 Likely mechanism with greatest influence on process Ocean Mechanical End of WY 9/30/2007 23:45 Time (days) between final season closure and end of WY 157.0 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 290.5 Totel days of closure including all partial closures 306.7 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in MPWMD 2006‐2007 annual mitigation report and Perry et al. 2006‐07 CCoWS report Table 7. WY 2006, Riverine Dynamics of Breaches and Closures Sustained WSE increase while In‐season Temporary closure closed Sustained breach* closure breach In‐season closure Sustained breach Early Closure Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Natural Natural Dry Season Events 10/1/2005 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/4/2005 9:00 Lowest lagoon WSE during closure, this WY 6.91 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 12/9/2005 4:15 WSE (ft) 7.89 Date‐Time of highest WSE post‐increase 12/21/05 15:30 WSE (ft) 9.58 Increase in WSE (ft) 1.69 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 20 Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 88.5 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/28/2005 11:45 2/10/2006 5:45 2/22/2006 12:15 WSE (ft) 11.35 12.83 12.74 Date‐Time of lowest WSE directly following breach 12/30/2005 22:45 2/10/2006 20:15 2/23/2006 1:30 WSE (ft) 6.42 5.33 5.06 WSE pre‐breach minus post‐breach (ft) 4.93 7.49 7.68 Time difference (days) 2.46 0.60 0.55 Time difference (hours) 59.00 14.50 13.25 Rate of WSE decline (ft/hr) 0.08 0.52 0.58 Mean daily flow rate (cfs) on day of breach 81 57 49 Mean daily flow rate (cfs) on day of lowest WSE following breach 82 57 47 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Riverine Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 2/6/2006 17:15 2/15/2006 21:00 WSE (ft) 5.40 5.08 Date‐Time of lagoon WSE fills to > 11 feet 2/8/2006 6:00 2/19/2006 23:00 WSE (ft) 11.01 11.00 Date‐Time of lagoon falls below WSE > 11 feet 2/10/2006 6:45 2/22/2006 14:00 WSE (ft) 10.75 11.35 Time (days) of WSE > 11 feet 2.0 2.6 Time (hours) of WSE > 11 feet 48.75 63.00 Mean daily flow rate (cfs) on day lowest WSE 69 49 Mean daily flow rate (cfs) on day WSE > 11 feet 63 55 Mean daily flow rate (cfs) on day WSE < 11 feet 57 49 Likely mechanism with greatest influence on closure process Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 6/21/2006 5:15 7/17/2006 9:00 WSE (ft) 10.53 10.14 Date‐Time of lowest WSE during WY closure 7/6/2006 7:30 9/4/2006 18:45 WSE (ft) 8.63 6.31 Time (days) difference highest minus lowest WSE 15.09 49.41 Time (hours) difference highest minus lowest WSE 362.25 1185.75 Highest WSE at closure minus lowest WSE during closure in this WY 1.89 3.83 Rate of decrease in WSE (ft/day) 0.005 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 36 13 Mean daily flow rate (cfs) on day of lowest WSE of dry season 27 0 Likely mechanism with greatest influence on process Mechanical Ocean End of WY 9/30/2006 23:45 Time (days) between final season closure and end of WY 75.6 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 164.1 Totel days of closure including all partial closures 183.9 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in MPWMD 2005‐2006 annual mitigation report and the Larson et al. 2005‐06 CCoWS report Table 8. WY 2005, Riverine Dynamics of Breaches and Closures Sustained WSE increase while closure closed Sustained breach* Early closure Final closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Dry Season Events 10/1/2004 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/7/2004 11:30 Lowest lagoon WSE during closure, this WY 6.37 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/16/2004 0:15 WSE (ft) 6.99 Date‐Time of highest WSE post‐increase 38281.36 WSE (ft) 8.39 Increase in WSE (ft) 1.39 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 90.7 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/30/2004 16:00 WSE (ft) 13.03 Date‐Time of lowest WSE directly following breach 1/2/2005 0:45 WSE (ft) 7.27 WSE pre‐breach minus post‐breach (ft) 5.76 Time difference (days) 2.36 Time difference (hours) 56.75 Rate of WSE decline (ft/hr) 0.10 Mean daily flow rate (cfs) on day of breach 532 Mean daily flow rate (cfs) on day of lowest WSE following breach 642 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours WSE (ft) Date‐Time of lagoon WSE fills to > 11 feet WSE (ft) Date‐Time of lagoon falls below WSE > 11 feet WSE (ft) Time (days) of WSE > 11 feet Time (hours) of WSE > 11 feet Mean daily flow rate (cfs) on day lowest WSE Mean daily flow rate (cfs) on day WSE > 11 feet Mean daily flow rate (cfs) on day WSE < 11 feet Likely mechanism with greatest influence on closure process Dry Season Closure Date‐Time of highest WSE at WY closure 7/10/2005 0:45 7/20/2005 1:45 WSE (ft) 9.52 8.66 Date‐Time of lowest WSE during WY closure 7/11/2005 23:30 8/29/2005 13:00 WSE (ft) 5.87 5.81 Time (days) difference highest minus lowest WSE 1.95 40.47 Time (hours) difference highest minus lowest WSE 46.75 971.25 Highest WSE at closure minus lowest WSE during closure in this WY 3.64 2.85 Rate of decrease in WSE (ft/day) 0.08 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 8.6 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2005 23:45 Time (days) between final season closure and end of WY 72.9 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 163.6 Totel days of closure including all partial closures 165.5 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in the Larson et al. 2004‐05 CCoSW report Table 9. WY 2004, Riverine Dynamics of Breaches and Closures Sustained WSE increase while In‐season Temporary In‐season Temporary In‐season WSE increase while closure closed Sustained breach* Closure breach Closure breach Closure Sustained breach Early Closure Final Closure closed Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Natural Natural Natural Dry Season Events 10/1/2003 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/2/2003 12:00 Lowest lagoon WSE during closure, this WY 5.86 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 12/8/2003 6:00 8/24/04 14:15 WSE (ft) 8.17 5.71 Date‐Time of highest WSE post‐increase 12/10/2003 12:45 8/29/04 2:15 WSE (ft) 11.18 7.23 Increase in WSE (ft) 3.01 1.53 Likely mechanism with greatest influence on WSE increase process Wave overtopping Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0 0 Date‐Time of most recent WSE > 11 ft prior to breach, this WY 12/11/2003 9:15 Time (days) between start of WY and first seasonal breach 90.6 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/30/2003 15:00 1/14/2004 17:30 1/20/2004 17:30 1/26/2004 15:30 WSE (ft) 13.22 12.35 11.82 12.0 Date‐Time of lowest WSE directly following breach 12/31/2003 1:00 1/15/2004 0:30 1/21/2004 4:00 1/26/2004 22:30 WSE (ft) 6.09 5.36 5.25 5.3 WSE pre‐breach minus post‐breach (ft) 7.13 6.99 6.57 6.72 Time difference (days) 0.42 0.29 0.44 0.29 Time difference (hours) 10 7 10.5 7 Rate of WSE decline (ft/hr) 0.71 1.00 0.63 0.96 Mean daily flow rate (cfs) on day of breach 416 45 34 28 Mean daily flow rate (cfs) on day of lowest WSE following breach 249 44 32 28 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Riverine Unknown Unknown Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 1/11/2004 21:00 1/17/2004 21:00 1/22/2004 4:45 4/20/2004 19:00 WSE (ft) 5.37 5.88 5.4 5.44 Date‐Time of lagoon WSE fills to > 11 feet 1/13/2004 1:00 1/19/2004 8:30 1/24/2004 11:00 4/25/2004 6:30 WSE (ft) 11.0 11.01 11.0 11.00 Date‐Time of lagoon falls below WSE > 11 feet 1/14/2004 19:00 1/20/2004 18:30 1/26/2004 18:15 4/27/2004 20:30 WSE (ft) 9.9 10.57 8.77 10.88 Time (days) of WSE > 11 feet 1.75 1.42 2.30 2.58 Time (hours) of WSE > 11 feet 42.0 34.0 55.25 62.0 Mean daily flow rate (cfs) on day lowest WSE 57 41 30 29 Mean daily flow rate (cfs) on day WSE > 11 feet 49 36 29 20 Mean daily flow rate (cfs) on day WSE < 11 feet 45 34 28 16 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 5/7/2004 3:30 WSE (ft) 9.95 Date‐Time of lowest WSE during WY closure or following break 7/18/2004 13:45 WSE (ft) 5.10 Time (days) difference highest minus lowest WSE 72.43 Time (hours) difference highest minus lowest WSE 1738.25 Highest WSE at closure minus lowest WSE during closure in this WY 4.85 Rate of decrease in WSE (ft/day) 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 11 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2004 23:45 Time (days) between final season closure and end of WY 146.8 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 237.5 Totel days of closure including all partial closures 245.5 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events as reported in the Smith et al. 2003‐04 CCoSW report Table 10. WY 2003, Riverine Dynamics of Breaches and Closures Sustained WSE increase while WSE increase while In‐season closure closed closed Sustained breach* Closure Sustained breach Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Dry Season Events 10/1/2002 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/15/2002 9:30 Lowest lagoon WSE during closure, this WY 5.56 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/15/2002 9:30 11/6/2002 0:30 WSE (ft) 5.56 7.59 Date‐Time of highest WSE post‐increase 10/22/2002 16:00 11/8/2002 17:15 WSE (ft) 7.86 11.53 Increase in WSE (ft) 2.30 3.94 Likely mechanism with greatest influence on WSE increase process Wave overtopping Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 00 Date‐Time of most recent WSE > 11 ft prior to breach, this WY 11/12/2002 1:45 Time (days) between start of WY and first seasonal breach 76.5 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/16/2002 12:15 6/18/2003 19:45 WSE (ft) 13.55 11.45 Date‐Time of lowest WSE directly following breach 12/16/2002 15:15 6/19/2003 0:15 WSE (ft) 7.14 5.29 WSE pre‐breach minus post‐breach (ft) 6.41 6.16 Time difference (days) 0.13 0.19 Time difference (hours) 3.00 4.50 Rate of WSE decline (ft/hr) 2.14 1.37 Mean daily flow rate (cfs) on day of breach 1250 25 Mean daily flow rate (cfs) on day of lowest WSE following breach 1250 25 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 6/14/2003 8:45 WSE (ft) 5.1 Date‐Time of lagoon WSE fills to > 11 feet 6/17/2003 11:45 WSE (ft) 11.0 Date‐Time of lagoon falls below WSE > 11 feet 6/18/2003 20:45 WSE (ft) 10.7 Time (days) of WSE > 11 feet 1.4 Time (hours) of WSE > 11 feet 33.0 Mean daily flow rate (cfs) on day lowest WSE 33 Mean daily flow rate (cfs) on day WSE > 11 feet 27 Mean daily flow rate (cfs) on day WSE < 11 feet 25 Likely mechanism with greatest influence on closure process Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 7/11/2003 22:30 WSE (ft) 7.98 Date‐Time of lowest WSE during WY closure or following break 8/8/2003 15:45 WSE (ft) 5.37 Time (days) difference highest minus lowest WSE 27.72 Time (hours) difference highest minus lowest WSE 665.25 Highest WSE at closure minus lowest WSE during closure in this WY 2.61 Rate of decrease in WSE (ft/day) 0.004 Mean daily flow rate (cfs) on day of highest WSE at closure 6.8 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2003 23:45 Time (days) between final season closure and end of WY 81.1 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 157.6 Totel days of closure including all partial closures 158.9 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in the Casagrande and Watson 2002‐03 CCoSW report Table 11. WY 2002, Riverine Dynamics of Breaches and Closures Sustained WSE increase while WSE increase while In‐season closure closed closed Sustained breach* Closure Sustained breach Early Closure Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Mechanical Natural Natural Dry Season Events 10/1/2001 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/8/2001 2:30 Lowest lagoon WSE during closure, this WY 6.76 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/8/2001 2:30 10/31/2001 0:15 WSE (ft) 6.76 6.97 Date‐Time of highest WSE post‐increase 10/16/2001 0:45 11/4/2001 17:00 WSE (ft) 8.24 8.16 Increase in WSE (ft) 1.48 1.19 Likely mechanism with greatest influence on WSE increase process Wave overtopping Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0 0
Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 63.6 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/3/2001 14:15 1/28/2002 16:45 WSE (ft) 13.39 12.32 Date‐Time of lowest WSE directly following breach 12/3/2001 22:30 1/29/2002 6:45 WSE (ft) 5.64 5.65 WSE pre‐breach minus post‐breach (ft) 7.75 6.67 Time difference (days) 0.34 0.58 Time difference (hours) 8.25 14.0 Rate of WSE decline (ft/hr) 0.94 0.48 Mean daily flow rate (cfs) on day of breach 402 53 Mean daily flow rate (cfs) on day of lowest WSE following breach 402 54 Likely mechanism with greatest influence on breaching process Mechnical/Riverine Mechnical/Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 1/26/2002 21:00 WSE (ft) 5.88 Date‐Time of lagoon WSE fills to > 11 feet 1/27/2002 15:45 WSE (ft) 11.00 Date‐Time of lagoon falls below WSE > 11 feet 1/28/2002 18:30 WSE (ft) 10.56 Time (days) of WSE > 11 feet 1.11 Time (hours) of WSE > 11 feet 26.75 Mean daily flow rate (cfs) on day lowest WSE 50 Mean daily flow rate (cfs) on day WSE > 11 feet 53 Mean daily flow rate (cfs) on day WSE < 11 feet 53 Likely mechanism with greatest influence on closure process Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 5/26/2002 9:15 6/4/2002 11:15 WSE (ft) 10.90 10.04 Date‐Time of lowest WSE during WY closure or following break 5/26/2002 20:15 8/25/2002 21:45 WSE (ft) 5.25 5.31 Time (days) difference highest minus lowest WSE 0.46 82.44 Time (hours) difference highest minus lowest WSE 11.00 1978.50 Highest WSE at closure minus lowest WSE during closure in this WY 5.65 4.73 Rate of decrease in WSE (ft/day) 0.514 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 18 11 Mean daily flow rate (cfs) on day of lowest WSE of dry season 18 0 Likely mechanism with greatest influence on process Ocean Ocean End of WY 9/30/2002 23:45 Time (days) between final season closure and end of WY 118.5 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 182.1 Totel days of closure including all partial closures 183.7 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in the Casagrande et al. 2001‐02 CCoSW report Table 12. WY 2001, Riverine Dynamics of Breaches and Closures Sustained WSE increase while closure closed Sustained breach* Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Dry Season Events 10/1/2000 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/9/2000 10:30 Lowest lagoon WSE during closure, this WY 6.82 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/21/2000 16:30 WSE (ft) 7.41 Date‐Time of highest WSE post‐increase 10/26/2000 15:30 WSE (ft) 9.08 Increase in WSE (ft) 4.96 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0
Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 102.68 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 1/11/2001 16:15 WSE (ft) 14.78 Date‐Time of lowest WSE directly following breach 1/11/2001 20:30 WSE (ft) 5.47 WSE pre‐breach minus post‐breach (ft) 9.31 Time difference (days) 0.18 Time difference (hours) 4.25 Rate of WSE decline (ft/hr) 2.19 Mean daily flow rate (cfs) on day of breach 148 Mean daily flow rate (cfs) on day of lowest WSE following breach 148 Likely mechanism with greatest influence on breaching process Mechnical/Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours WSE (ft) Date‐Time of lagoon WSE fills to > 11 feet WSE (ft) Date‐Time of lagoon falls below WSE > 11 feet WSE (ft) Time (days) of WSE > 11 feet Time (hours) of WSE > 11 feet Mean daily flow rate (cfs) on day lowest WSE Mean daily flow rate (cfs) on day WSE > 11 feet Mean daily flow rate (cfs) on day WSE < 11 feet Likely mechanism with greatest influence on closure process Dry Season Closure Date‐Time of highest WSE at WY closure 6/13/2001 5:30 WSE (ft) 9.87 Date‐Time of lowest WSE during WY closure or following break 8/23/2001 5:45 WSE (ft) 5.58 Time (days) difference highest minus lowest WSE 71.01 Time (hours) difference highest minus lowest WSE 1704.25 Highest WSE at closure minus lowest WSE during closure in this WY 4.29 Rate of decrease in WSE (ft/day) 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 8.5 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/2001 23:45 Time (days) between final season closure and end of WY 109.8 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 212.4 Totel days of closure including all partial closures 212.4 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Some breaching and/or closure events were reported in the Watson et al. 2000‐01 CCoSW report Table 13. WY 2000, Riverine Dynamics of Breaches and Closures Sustained WSE increase while closure closed Sustained breach* Early Closure Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Dry Season Events 10/1/1999 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/6/1999 18:00 Lowest lagoon WSE during closure, this WY 5.93 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/25/1999 4:45 WSE (ft) 6.23 Date‐Time of highest WSE post‐increase 10/28/1999 18:00 WSE (ft) 10.07 Increase in WSE (ft) 3.84 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0
Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 115.1 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 1/24/2000 2:15 WSE (ft) 14.05 Date‐Time of lowest WSE directly following breach 1/24/2000 22:30 WSE (ft) 6.85 WSE pre‐breach minus post‐breach (ft) 7.2 Time difference (days) 0.84 Time difference (hours) 20.25 Rate of WSE decline (ft/hr) 0.36 Mean daily flow rate (cfs) on day of breach 1000 Mean daily flow rate (cfs) on day of lowest WSE following breach 1000 Likely mechanism with greatest influence on breaching process Mechnical/Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours WSE (ft) Date‐Time of lagoon WSE fills to > 11 feet WSE (ft) Date‐Time of lagoon falls below WSE > 11 feet WSE (ft) Time (days) of WSE > 11 feet Time (hours) of WSE > 11 feet Mean daily flow rate (cfs) on day lowest WSE Mean daily flow rate (cfs) on day WSE > 11 feet Mean daily flow rate (cfs) on day WSE < 11 feet Likely mechanism with greatest influence on closure process Dry Season Closure Date‐Time of highest WSE at WY closure 4/24/2000 11:15 5/6/2000 2:30 WSE (ft) 10.35 10.70 Date‐Time of lowest WSE during WY closure or following break 5/2/2000 18:45 9/16/2000 10:45 WSE (ft) 8.11 5.67 Time (days) difference highest minus lowest WSE 8.31 133.34 Time (hours) difference highest minus lowest WSE 199.50 3200.25 Highest WSE at closure minus lowest WSE during closure in this WY 2.24 5.03 Rate of decrease in WSE (ft/day) 0.011 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 102 65 Mean daily flow rate (cfs) on day of lowest WSE of dry season 75 0 Likely mechanism with greatest influence on process Ocean Ocean End of WY 9/30/2000 23:45 Time (days) between final season closure and end of WY 147.9 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 263.0 Totel days of closure including all partial closures 271.3 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 2000 Table 14. WY 1999, Riverine Dynamics of Breaches and Closures WSE increase Temporary In‐season Temporary In‐season Temporary Sustained closure while closed Temporary breach In‐season Closure Temporary breach In‐season Closure Temporary breach In‐season Closure Sustained breach* In‐season Closure breach Closure breach Closure Sustained breach Early Closure breach Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Natural Natural Natural Dry Season Events 10/1/1998 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/1/1998 0:00 Lowest lagoon WSE during closure, this WY 10.01 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 23 Date‐Time of lowest WSE prior to significant increase in WSE 10/24/1998 9:45 WSE (ft) 10.71 Date‐Time of highest WSE post‐increase 11/3/1998 12:00 WSE (ft) 12.75 Increase in WSE (ft) 2.04 Likely mechanism with greatest influence on WSE increase process Riverine Mean daily flow rate (cfs) on day of highest WSE 22 Date‐Time of most recent WSE > 11 ft prior to breach, this WY 10/25/1998 9:15 Time (days) between start of WY and first seasonal breach 33.5 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 11/3/1998 12:00 11/10/1998 18:15 11/19/1998 13:00 11/26/1998 13:00 1/2/1999 15:45 1/8/1999 17:45 1/16/1999 18:45 6/17/1999 20:00 WSE (ft) 12.75 11.86 12.65 12.59 12.13 12.55 12.70 12.50 Date‐Time of lowest WSE directly following breach 11/4/1998 6:30 11/11/1998 4:30 11/19/1998 22:00 11/27/1998 0:30 1/2/1999 22:45 1/10/1999 1:00 1/16/1999 23:30 6/18/1999 13:30 WSE (ft) 5.00 5.02 5.19 5.26 5.40 5.05 6.67 5.27 WSE pre‐breach minus post‐breach (ft) 7.75 6.84 7.46 7.33 6.73 7.50 6.03 0.73 Time difference (days) 0.77 0.43 0.38 0.48 0.29 1.30 0.20 17.50 Time difference (hours) 18.50 10.25 9.00 11.50 7.00 31.25 4.75 7.23 Rate of WSE decline (ft/hr) 0.42 0.67 0.83 0.64 0.96 0.24 1.27 0.41 Mean daily flow rate (cfs) on day of breach 21 24 24 25 13 10 10 27 Mean daily flow rate (cfs) on day of lowest WSE following breach 21 31 24 27 13 10 10 26 Likely mechanism with greatest influence on breaching process Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 11/4/1998 6:30 11/11/1998 4:30 11/19/1998 22:00 12/28/1998 1:45 1/2/1999 22:45 1/10/1999 1:00 WSE (ft) 5.00 5.02 5.19 5.40 5.40 5.05 Date‐Time of lagoon WSE fills to > 11 feet 11/8/1998 2:15 11/14/1998 9:30 11/22/1998 13:15 12/31/1998 16:15 1/5/1999 4:45 1/13/1999 8:00 WSE (ft) 11.00 11.00 11.02 11.00 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 11/10/1998 20:15 11/19/1998 15:00 11/26/1998 14:00 1/2/1999 17:15 1/8/1999 18:45 1/16/1999 21:00 WSE (ft) 10.80 10.98 8.60 9.97 9.46 10.89 Time (days) of WSE > 11 feet 2.75 5.15 3.99 1.98 3.54 3.45 Time (hours) of WSE > 11 feet 66.00 123.50 95.75 47.50 85.00 82.75 Mean daily flow rate (cfs) on day lowest WSE 21 31 24 17 13 10 Mean daily flow rate (cfs) on day WSE > 11 feet 24 22 22 15 11 10 Mean daily flow rate (cfs) on day WSE < 11 feet 24 24 25 13 10 10 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Ocean Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 5/27/1999 0:00 7/4/1999 6:00 WSE (ft) 9.20 10.52 Date‐Time of lowest WSE during WY closure or following break 6/12/1999 17:30 8/18/1999 13:00 WSE (ft) 8.06 5.38 Time (days) difference highest minus lowest WSE 16.73 45.29 Time (hours) difference highest minus lowest WSE 401.50 1087.00 Highest WSE at closure minus lowest WSE during closure in this WY 1.14 5.14 Rate of decrease in WSE (ft/day) 0.003 0.005 Mean daily flow rate (cfs) on day of highest WSE at closure 53 7.2 Mean daily flow rate (cfs) on day of lowest WSE of dry season 34 0 Likely mechanism with greatest influence on process Unknown Ocean End of WY 9/30/1999 23:45 Time (days) between final season closure and end of WY 88.74 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 122.2 Totel days of closure including all partial closures 159.8 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 1999 Table 15. WY 1998, Riverine Dynamics of Breaches and Closures WSE increase Sustained Sustained closure while closed Sustained breach* In‐season Closure Temporary breach In‐season Closure breach Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Mechanical Mechanical Unknown Dry Season Events 10/1/1997 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/29/1997 21:00 Lowest lagoon WSE during closure, this WY 7.34 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 11/9/1997 17:45 WSE (ft) 8.16 Date‐Time of highest WSE post‐increase 11/15/1997 12:00 WSE (ft) 10.65 Increase in WSE (ft) 2.49 Likely mechanism with greatest influence on WSE increase process Ocean Mean daily flow rate (cfs) on day of highest WSE 0 Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 66.4 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/6/1997 10:15 12/30/1997 16:45 1/3/1998 17:30 WSE (ft) 12.36 12.66 12.12 Date‐Time of lowest WSE directly following breach 12/7/1997 0:45 12/30/1997 22:15 1/3/1998 23:30 WSE (ft) 6.57 5.40 5.36 WSE pre‐breach minus post‐breach (ft) 5.79 7.26 6.76 Time difference (days) 0.60 0.23 0.25 Time difference (hours) 14.5 5.5 6 Rate of WSE decline (ft/hr) 0.40 1.32 1.13 Mean daily flow rate (cfs) on day of breach 112 12 29 Mean daily flow rate (cfs) on day of lowest WSE following breach 135 12 29 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Mechanical Mechanical Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 12/26/1997 18:45 12/30/1997 22:15 WSE (ft) 5.45 5.40 Date‐Time of lagoon WSE fills to > 11 feet 12/28/1997 14:30 1/2/1998 15:45 WSE (ft) 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 12/30/1997 18:30 1/3/1998 18:45 WSE (ft) 9.88 10.10 Time (days) of WSE > 11 feet 2.17 1.07 Time (hours) of WSE > 11 feet 52.0 25.7 Mean daily flow rate (cfs) on day lowest WSE 18 12 Mean daily flow rate (cfs) on day WSE > 11 feet 15 11 Mean daily flow rate (cfs) on day WSE < 11 feet 12 29 Likely mechanism with greatest influence on closure process Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 6/12/1998 0:00 WSE (ft) 8.85 Date‐Time of lowest WSE during WY closure or following break 8/31/1998 2:30 WSE (ft) 7.16 Time (days) difference highest minus lowest WSE 80.10 Time (hours) difference highest minus lowest WSE 1922.50 Highest WSE at closure minus lowest WSE during closure in this WY 1.69 Rate of decrease in WSE (ft/day) 0.001 Mean daily flow rate (cfs) on day of highest WSE at closure 172 Mean daily flow rate (cfs) on day of lowest WSE of dry season 23 Likely mechanism with greatest influence on process Unknown End of WY 9/30/1998 23:45 Time (days) between final season closure and end of WY 110.99 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 177.4 Totel days of closure including all partial closures 180.7 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 1998 Table 16. WY 1997, Riverine Dynamics of Breaches and Closures WSE increase WSE increase Sustained closure while closed Sustained breach* Final closure while closed Breach Type Mechnical, Natural, or Unknown Mechanical Natural Dry Season Events 10/1/1996 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/4/1996 11:15 Lowest lagoon WSE during closure, this WY 6.10 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/4/1996 11:15 9/17/1997 23:45 WSE (ft) 6.10 6.16 Date‐Time of highest WSE post‐increase 10/8/1996 9:30 9/25/1997 22:00 WSE (ft) 9.20 10.48 Increase in WSE (ft) 3.10 4.32 Likely mechanism with greatest influence on WSE increase process Ocean Ocean Mean daily flow rate (cfs) on day of highest WSE 00
Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 69.6 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/9/1996 13:15 WSE (ft) 12.34 Date‐Time of lowest WSE directly following breach 12/10/1996 4:30 WSE (ft) 8.34 WSE pre‐breach minus post‐breach (ft) 4 Time difference (days) 0.64 Time difference (hours) 15.25 Rate of WSE decline (ft/hr) 0.26 Mean daily flow rate (cfs) on day of breach 27 Mean daily flow rate (cfs) on day of lowest WSE following breach 879 Likely mechanism with greatest influence on breaching process Mechanical Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours WSE (ft) Date‐Time of lagoon WSE fills to > 11 feet WSE (ft) Date‐Time of lagoon falls below WSE > 11 feet WSE (ft) Time (days) of WSE > 11 feet Time (hours) of WSE > 11 feet Mean daily flow rate (cfs) on day lowest WSE Mean daily flow rate (cfs) on day WSE > 11 feet Mean daily flow rate (cfs) on day WSE < 11 feet Likely mechanism with greatest influence on closure process Dry Season Closure Date‐Time of highest WSE at WY closure 5/18/1997 23:00 WSE (ft) 9.89 Date‐Time of lowest WSE during WY closure or following break 7/31/1997 16:00 WSE (ft) 5.51 Time (days) difference highest minus lowest WSE 73.71 Time (hours) difference highest minus lowest WSE 1769.00 Highest WSE at closure minus lowest WSE during closure in this WY 4.38 Rate of decrease in WSE (ft/day) 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 13 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/1997 23:45 Time (days) between final season closure and end of WY 135.0 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 204.6 Totel days of closure including all partial closures 204.6 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 1997 Table 17. WY 1996, Riverine Dynamics of Breaches and Closures Sustained Sustained closure Sustained breach* In‐season closure Temporary breach In‐season closure Temporary breach In‐season closure breach Final closure Breach Type Mechnical, Natural, or Unknown Mechanical Mechanical Mechanical Natural Natural Dry Season Events 10/1/1995 0:00 Date‐Time of lowest lagoon WSE prior to breach 11/12/1995 10:15 Lowest lagoon WSE during closure, this WY 7.12 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 2.50 Date‐Time of lowest WSE prior to significant increase in WSE WSE (ft) Date‐Time of highest WSE post‐increase WSE (ft) Increase in WSE (ft) Likely mechanism with greatest influence on WSE increase process Mean daily flow rate (cfs) on day of highest WSE Date‐Time of most recent WSE > 11 ft prior to breach, this WY 12/13/1995 2:45 Time (days) between start of WY and first seasonal breach 73.8 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 12/13/1995 18:30 12/24/1995 19:30 12/27/1995 22:30 1/2/1996 9:45 WSE (ft) 11.68 11.74 12.01 11.91 Date‐Time of lowest WSE directly following breach 12/14/1995 0:15 12/24/1995 22:30 12/28/1995 2:15 1/2/1996 14:30 WSE (ft) 5.65 5.86 6.95 5.37 WSE pre‐breach minus post‐breach (ft) 6.03 5.88 5.06 6.54 Time difference (days) 0.24 0.13 0.16 0.20 Time difference (hours) 5.75 3 3.75 4.75 Rate of WSE decline (ft/hr) 1.05 1.96 1.35 1.38 Mean daily flow rate (cfs) on day of breach 36 35 28 25 Mean daily flow rate (cfs) on day of lowest WSE following breach 36 35 24 25 Likely mechanism with greatest influence on breaching process Mechanical Riverine Riverine Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 12/21/1995 19:30 12/24/1995 22:30 12/29/1995 0:15 WSE (ft) 5.36 5.86 6.30 Date‐Time of lagoon WSE fills to > 11 feet 12/23/1995 15:00 12/26/1995 10:00 12/31/1995 16:45 WSE (ft) 11.00 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 12/24/1995 20:45 12/28/1995 0:00 1/2/1996 12:30 WSE (ft) 10.64 10.69 10.77 Time (days) of WSE > 11 feet 1.24 1.58 1.82 Time (hours) of WSE > 11 feet 29.8 38.0 43.8 Mean daily flow rate (cfs) on day lowest WSE 34 35 24 Mean daily flow rate (cfs) on day WSE > 11 feet 35 28 27 Mean daily flow rate (cfs) on day WSE < 11 feet 35 24 25 Likely mechanism with greatest influence on closure process Ocean Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 7/1/1996 0:15 WSE (ft) 10.37 Date‐Time of lowest WSE during WY closure or following break 8/28/1996 19:00 WSE (ft) 5.49 Time (days) difference highest minus lowest WSE 58.78 Time (hours) difference highest minus lowest WSE 1410.75 Highest WSE at closure minus lowest WSE during closure in this WY 4.88 Rate of decrease in WSE (ft/day) 0.003 Mean daily flow rate (cfs) on day of highest WSE at closure 8.5 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/1996 23:45 Time (days) between final season closure and end of WY 91.98 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 165.8 Totel days of closure including all partial closures 170.4 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 1996 Table 18. WY 1995, Riverine Dynamics of Breaches and Closures WSE increase while Sustained closure Sustained breach* Final Closure closed Breach Type Mechnical, Natural, or Unknown Mechanical Natural Dry Season Events 10/1/1994 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/1/1994 21:15 Lowest lagoon WSE during closure, this WY 5.96 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 9/6/1995 9:30 WSE (ft) 5.59 Date‐Time of highest WSE post‐increase 9/24/1995 0:30 WSE (ft) 10.43 Increase in WSE (ft) 4.84 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE
Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 101.3 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 1/10/1995 6:15 WSE (ft) 10.51 Date‐Time of lowest WSE directly following breach 1/12/1995 1:15 WSE (ft) 6.39 WSE pre‐breach minus post‐breach (ft) 4.12 Time difference (days) 1.79 Time difference (hours) 43 Rate of WSE decline (ft/hr) 0.10 Mean daily flow rate (cfs) on day of breach 6070 Mean daily flow rate (cfs) on day of lowest WSE following breach 746 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours WSE (ft) Date‐Time of lagoon WSE fills to > 11 feet WSE (ft) Date‐Time of lagoon falls below WSE > 11 feet WSE (ft) Time (days) of WSE > 11 feet Time (hours) of WSE > 11 feet Mean daily flow rate (cfs) on day lowest WSE Mean daily flow rate (cfs) on day WSE > 11 feet Mean daily flow rate (cfs) on day WSE < 11 feet Likely mechanism with greatest influence on closure process Dry Season Closure Date‐Time of highest WSE at WY closure 8/9/1995 0:00 WSE (ft) 9.73 Date‐Time of lowest WSE during WY closure or following break 9/6/1995 9:30 WSE (ft) 5.59 Time (days) difference highest minus lowest WSE 28.40 Time (hours) difference highest minus lowest WSE 681.50 Highest WSE at closure minus lowest WSE during closure in this WY 4.14 Rate of decrease in WSE (ft/day) 0.006 Mean daily flow rate (cfs) on day of highest WSE at closure 3.7 Mean daily flow rate (cfs) on day of lowest WSE of dry season 3 Likely mechanism with greatest influence on process Ocean End of WY 9/30/1995 23:45 Time (days) between final season closure and end of WY 52.99 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 154.3 Totel days of closure including all partial closures 154.3 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures Mechanical breach on January 9, 1995 in anticipation of flood flows, James, 2005 (p 10) Table 19. WY 1994, Riverine Dynamics of Breaches and Closures Sustained WSE increase Temporary Temporary closure while closed Sustained Breach* In‐season closure breach In‐season closure breach Final closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Natural Dry Season Events 10/1/1993 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/3/1993 12:00 Lowest lagoon WSE during closure, this WY 5.44 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 11/6/1993 8:15 WSE (ft) 7.43 Date‐Time of highest WSE post‐increase 11/13/1993 10:45 WSE (ft) 8.87 Increase in WSE (ft) 1.44 Likely mechanism with greatest influence on WSE increase process Ocean Mean daily flow rate (cfs) on day of highest WSE 0.00
Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 139.9 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 2/17/1994 22:15 3/18/1994 15:00 3/27/1994 17:00 WSE (ft) 11.69 11.62 12.15 Date‐Time of lowest WSE directly following breach 2/19/1994 15:45 3/19/1994 14:30 3/27/1994 20:00 WSE (ft) 6.45 7.80 5.81 WSE pre‐breach minus post‐breach (ft) 5.24 3.82 6.34 Time difference (days) 1.73 0.98 0.13 Time difference (hours) 41.5 23.5 3 Rate of WSE decline (ft/hr) 0.13 0.16 2.11 Mean daily flow rate (cfs) on day of breach 106 22 20 Mean daily flow rate (cfs) on day of lowest WSE following breach 203 22 20 Likely mechanism with greatest influence on breaching process Mechanical/Riverine Riverine Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 3/13/1994 9:00 3/19/1994 15:45 WSE (ft) 5.6 7.8 Date‐Time of lagoon WSE fills to > 11 feet 3/16/1994 20:30 3/24/1994 7:45 WSE (ft) 11.00 11.00 Date‐Time of lagoon falls below WSE > 11 feet 3/18/1994 17:45 3/27/1994 18:00 WSE (ft) 10.93 10.05 Time (days) of WSE > 11 feet 1.89 3.39 Time (hours) of WSE > 11 feet 45.3 81.3 Mean daily flow rate (cfs) on day lowest WSE 31 22 Mean daily flow rate (cfs) on day WSE > 11 feet 24 20 Mean daily flow rate (cfs) on day WSE < 11 feet 22 20 Likely mechanism with greatest influence on closure process Ocean Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 4/3/1994 3:45 WSE (ft) 10.66 Date‐Time of lowest WSE during WY closure or following break 8/29/1994 16:45 WSE (ft) 5.44 Time (days) difference highest minus lowest WSE 148.54 Time (hours) difference highest minus lowest WSE 3565.00 Highest WSE at closure minus lowest WSE during closure in this WY 5.22 Rate of decrease in WSE (ft/day) 0.001 Mean daily flow rate (cfs) on day of highest WSE at closure 8.2 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/1994 23:45 Time (days) between final season closure and end of WY 180.83 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 320.8 Totel days of closure including all partial closures 326.0 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 1994 Table 20. WY 1993, Riverine Dynamics of Breaches and Closures Sustained WSE increase while Sustained In‐season closure closed Breach* Closure Sustained Breach Final Closure Breach Type Mechnical, Natural, or Unknown Mechanical Natural Natural Dry Season Events 10/1/1992 0:00 Date‐Time of lowest lagoon WSE prior to breach 10/19/1992 6:00 Lowest lagoon WSE during closure, this WY 6.19 Mean daily flow rate (cfs) on day of lowest WSE prior to 1st reported breach 0 Date‐Time of lowest WSE prior to significant increase in WSE 10/24/1992 8:30 WSE (ft) 7.38 Date‐Time of highest WSE post‐increase 10/28/1992 17:00 WSE (ft) 10.06 Increase in WSE (ft) 2.68 Likely mechanism with greatest influence on WSE increase process Wave overtopping Mean daily flow rate (cfs) on day of highest WSE 0 Date‐Time of most recent WSE > 11 ft prior to breach, this WY none Time (days) between start of WY and first seasonal breach 98.5 Breachs and Closures during rainy season Date‐Time of highest WSE at time of breach 1/7/1993 11:00 6/3/1993 13:30 WSE (ft) 12.74 12.07 Date‐Time of lowest WSE directly following breach 1/7/1993 19:30 6/3/1993 19:30 WSE (ft) 6.23 5.71 WSE pre‐breach minus post‐breach (ft) 6.51 6.36 Time difference (days) 0.35 0.25 Time difference (hours) 8.5 6 Rate of WSE decline (ft/hr) 0.77 1.06 Mean daily flow rate (cfs) on day of breach 697 47 Mean daily flow rate (cfs) on day of lowest WSE following breach 697 47 Likely mechanism with greatest influence on breaching process Mechanical Riverine Date‐Time of lowest lagoon WSE prior to next WSE > 11 feet for > 24 hours 5/28/1993 15:00 WSE (ft) 5.46 Date‐Time of lagoon WSE fills to > 11 feet 6/2/1993 3:30 WSE (ft) 11.02 Date‐Time of lagoon falls below WSE > 11 feet 6/3/1993 14:50 WSE (ft) 8.66 Time (days) of WSE > 11 feet 1.47 Time (hours) of WSE > 11 feet 35.3 Mean daily flow rate (cfs) on day lowest WSE 28 Mean daily flow rate (cfs) on day WSE > 11 feet 53 Mean daily flow rate (cfs) on day WSE < 11 feet 47 Likely mechanism with greatest influence on closure process Ocean Dry Season Closure Date‐Time of highest WSE at WY closure 7/3/1993 1:00 WSE (ft) 8.77 Date‐Time of lowest WSE during WY closure or following break 9/30/1993 23:30 WSE (ft) 5.52 Time (days) difference highest minus lowest WSE 89.94 Time (hours) difference highest minus lowest WSE 2158.50 Highest WSE at closure minus lowest WSE during closure in this WY 3.25 Rate of decrease in WSE (ft/day) 0.002 Mean daily flow rate (cfs) on day of highest WSE at closure 4.9 Mean daily flow rate (cfs) on day of lowest WSE of dry season 0 Likely mechanism with greatest influence on process Ocean End of WY 9/30/1993 23:45 Time (days) between final season closure and end of WY 89.95 Total days of lagoon closure in this WY (pre‐ and post‐rainy season) 188.4 Totel days of closure including all partial closures 189.9 Notes Water year (WY) is defined as the time period beginning October 1st of a given year and ending September 30th the following year All WSE elevations are in NAVD88, feet Breach types are based on professional judgement, available records, and personal communications with staff knowledgeable of breaching operations * indicates breach data used for rate of lagoon draining in Table 3 Sustained closure is defined from October 1st of each water year until the first breach Temporary breach is defined as lagoon being open to tidal influence for < 7 consecutive days Sustained breach is defined as the lagoon remaining open to tidal influences for > 7 consecutive days In‐season closure is defined as the time period during the wet season (approximately October ‐ May of each WY) when lagoon WSE > 11 feet persists for > 24 hours Early closure is defined as lagoon closing due to mechanical or ocean processes shortly (approximately 1 week to 1 month early) before a final closure Final closure is defined as lagoon closed to ocean processes until the following water year Significant increase in WSE is defined as an increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Wave overtopping is defined as increase in lagoon WSE of > 1 foot when flows are zero and lagoon is closed to the ocean Total days of lagoon closure included days between start of WY and 1st breach, days between final season closure and end of WY, and days of in‐season closures No record of breaching and/or closing events for WY 1993